Science.gov

Sample records for 6df galaxy survey

  1. The SAMI IFU Galaxy Survey

    NASA Astrophysics Data System (ADS)

    Konstantopoulos, Iraklis; Croom, S. M.; Lawrence, J. S.; Bland-Hawthorn, J.; Bryant, J.; Fogarty, L.; Richards, S.; Goodwin, M.; Farrell, T.; Miziarski, S.; Heald, R.; Jones, D.; Lee, S.; Colless, M.; Brough, S.; Hopkins, A. M.; Bauer, A. E.; Birchall, M. N.; Ellis, S. C.; Horton, A. J.; Leon-Saval, S. G.; Lewis, G. F.; Lopez-Sanchez, A. R.; Min, S.; Trinh, C.; Trowland, H.; SAMI Team

    2013-01-01

    The past decade has seen the undertaking of several large spectroscopic surveys, which have enhanced our understanding of the processes that govern galaxy evolution. The next generation of surveys will allot not a fibre, but an Integral Field Unit on each galaxy, in order to push that understanding to the next level: spatially resolved spectroscopy. With a target list in the thousands of galaxies, the Sydney-AAO Multi-object Integral Field Spectrograph (SAMI) Survey will boldly push forward in this domain. On behalf of the SAMI team, I will present an overview of the capabilities of this innovative multiplexed IFU spectrograph and the survey it is undertaking, as well as highlight some early science.

  2. Neutral hydrogen survey of andromeda galaxy.

    PubMed

    Brundage, W D; Kraus, J D

    1966-07-22

    A neutral hydrogen survey of the Andromeda galaxy (M31) has been conducted with the 260-foot (80m) Ohio State University radio telescope. The neutral hydrogen is concentrated in the spiral arm regions, with but relatively small amounts near the center of the galaxy. Similar deficiencies have been found near the center of M33 and our galaxy, suggesting similar evolutionary processes in the three galaxies.

  3. Galactic surveys: Small galaxies are growing smaller

    NASA Astrophysics Data System (ADS)

    Phillipps, Steve

    2004-12-01

    Galaxies are not always giant collections of billions of stars. Since the 1930s, when Harlow Shapley discovered the first dwarf spheroidal galaxies, technology has allowed the detection of ever fainter galaxies in our immediate neighbourhood. Our galaxy is now known to have a whole retinue of very small satellite galaxies, the lowest luminosity examples of which can hardly outshine one massive star. Some galaxies appear to be getting physically smaller. Evidence for this is found in the streams of stars detected around our galaxy and elsewhere and in galaxies that appear to have had their outer regions truncated. Recent surveys of galaxy clusters have revealed another new class of object, the ultra-compact dwarfs. Though no less luminous than other dwarf galaxies, their physical sizes, of order 20 pc, are far below anything previously seen. They are reminiscent of the nuclei of dE,N type galaxies and may well be descended from them via some destructive processes within galaxy clusters.

  4. Local Group Galaxy Emission-line Survey

    NASA Astrophysics Data System (ADS)

    Blaha, Cindy; Baildon, Taylor; Mehta, Shail; Garcia, Edgar; Massey, Philip; Hodge, Paul W.

    2015-01-01

    We present the results of the Local Group Galaxy Emission-line Survey of Hα emission regions in M31, M33 and seven dwarf galaxies in (NGC6822, IC10, WLM, Sextans A and B, Phoenix and Pegasus). Using data from the Local Group Galaxy Survey (LGGS - see Massey et al, 2006), we used continuum-subtracted Ha emission line images to define emission regions with a faint flux limit of 10 -17 ergs-sec-1-cm-2above the background. We have obtained photometric measurements for roughly 7450 Hα emission regions in M31, M33 and five of the seven dwarf galaxies (no regions for Phoenix or Pegasus). Using these regions, with boundaries defined by Hα-emission flux limits, we also measured fluxes for the continuum-subtracted [OIII] and [SII] images and constructed a catalog of Hα fluxes, region sizes and [OIII]/ Hα and [SII]/ Hα line ratios. The HII region luminosity functions and size distributions for the spiral galaxies M31 and M33 are compared with those of the dwarf galaxies NGC 6822 and IC10. For M31 and M33, the average [SII]/ Hα and [OIII]/ Hα line ratios, plotted as a function of galactocentric radius, display a linear trend with shallow slopes consistent with other studies of metallicity gradients in these galaxies. The galaxy-wide averages of [SII]/ Hα line ratios correlate with the masses of the dwarf galaxies following the previously established dwarf galaxy mass-metallicity relationship. The slope of the luminosity functions for the dwarf galaxies varies with galaxy mass. The Carleton Catalog of this Local Group Emission-line Survey will be made available on-line.

  5. SAMI Galaxy Survey: Spectrally Dissecting 3400 Galaxies By the Dozen

    NASA Astrophysics Data System (ADS)

    Cecil, Gerald N.; Croom, S.; The SAMI Galaxy Survey Team

    2014-01-01

    More than 440 mapped, less than 3000 to go in the Sydney-AAO Multi-object IFU (SAMI) Galaxy Survey! SAMI uses novel, photonic fused-optical fiber “hexabundles” that were developed successfully at The University of Sydney and the Australian Astronomical Observatory AAO), with support from the Australian Research Council Centre of Excellence for All-Sky Astrophysics (CAASTRO). The SAMI Galaxy Survey, led by Assoc. Prof. Croom, is backed by an international team. This spectro-bolometric survey mitigates against “aperture effects” that may mislead when stacking single-fiber galaxy spectra. We seek to answer questions such as “what is the physical role of environment in galaxy evolution? How is stellar mass growth and angular momentum development related in galaxies? How does gas get into and out of galaxies, and how do such flows drive star formation?” SAMI maps stellar and gas properties with 13 integral-field units (IFU) plugged onto a dozen galaxies over the 1° field of the AAT prime-focus corrector. 78% of each bundle's area is filled by sixty-one 1.6-arcsec diameter fibers that are packed closely into concentric circles then their etched, thinned cladding is fused without deforming their cores. The fiber hexabundles route to the bench-mounted AAOmega double-beam spectrograph to cover simultaneously 373-570 nm at R=1730 and 620-735 nm at R=4500. Full spatial resolution of the observing site is recovered by dithered exposures totaling 3.5 hours per field. Target stellar masses generally exceed 108 M⊙, and span a range of environments: ˜650 are within clusters of virial mass 1014-15 M⊙ at 0.03 < z < 0.06, the rest are in the z < 0.1 field with extensive frequency data ancillary to the GAMA Survey. We display some key early results of major science themes being addressed by the SAMI survey team, from rotation curve dependence on group halo mass, through galaxy winds and AGN feedback mechanisms, to oxygen abundance gradients, kinematic decomposition

  6. Galaxy redshift surveys with sparse sampling

    SciTech Connect

    Chiang, Chi-Ting; Wullstein, Philipp; Komatsu, Eiichiro; Jee, Inh; Jeong, Donghui; Blanc, Guillermo A.; Ciardullo, Robin; Gronwall, Caryl; Hagen, Alex; Schneider, Donald P.; Drory, Niv; Fabricius, Maximilian; Landriau, Martin; Finkelstein, Steven; Jogee, Shardha; Cooper, Erin Mentuch; Tuttle, Sarah; Gebhardt, Karl; Hill, Gary J.

    2013-12-01

    Survey observations of the three-dimensional locations of galaxies are a powerful approach to measure the distribution of matter in the universe, which can be used to learn about the nature of dark energy, physics of inflation, neutrino masses, etc. A competitive survey, however, requires a large volume (e.g., V{sub survey} ∼ 10Gpc{sup 3}) to be covered, and thus tends to be expensive. A ''sparse sampling'' method offers a more affordable solution to this problem: within a survey footprint covering a given survey volume, V{sub survey}, we observe only a fraction of the volume. The distribution of observed regions should be chosen such that their separation is smaller than the length scale corresponding to the wavenumber of interest. Then one can recover the power spectrum of galaxies with precision expected for a survey covering a volume of V{sub survey} (rather than the volume of the sum of observed regions) with the number density of galaxies given by the total number of observed galaxies divided by V{sub survey} (rather than the number density of galaxies within an observed region). We find that regularly-spaced sampling yields an unbiased power spectrum with no window function effect, and deviations from regularly-spaced sampling, which are unavoidable in realistic surveys, introduce calculable window function effects and increase the uncertainties of the recovered power spectrum. On the other hand, we show that the two-point correlation function (pair counting) is not affected by sparse sampling. While we discuss the sparse sampling method within the context of the forthcoming Hobby-Eberly Telescope Dark Energy Experiment, the method is general and can be applied to other galaxy surveys.

  7. Deep multicolor surveys of the galaxy population

    NASA Astrophysics Data System (ADS)

    Szokoly, Gyula Pal

    1999-10-01

    I present various surveys that benefit from the tremendous improvements in observational astronomy in recent years and I develop new techniques to analyze data obtained in these new generation of surveys. In participation of upcoming, very deep near-infrared galaxy surveys, I constructed a survey aimed at determining the near-infrared luminosity function of galaxies. The evolutionary effects are much weaker at the red end of the atmospheric window ranging from the near- ultraviolet to about 2.2 μ m than in the optical and UV bands, as the infrared light coming from a galaxy is dominated by the old stellar population, while optical luminosity is strongly affected by the star formation history of galaxies. Measuring the luminosity function of galaxies is essential to interpret future surveys. Utilizing my deep, large area, multi-color optical galaxy survey, I studied the structure evolution of the Universe on cosmologically relevant scales. The multicolor nature of the survey (B, V, R and I bands) made it possible to estimate the radial distance to a very large number of galaxies very efficiently. Using these photometric redshifts, one can reduce the effects of galaxy evolution by analyzing galaxies at roughly the same redshift (lookback time). Due to the large area (about 1.5 square degrees) and very faint limiting magnitude (I = 23.8), structure evolution can be studied with a very high precision. I also propose a new object detection technique to replace traditional methods that use a single band or an arbitrarily co-added image. Our new technique uses all available bands of a survey and provides a nearly optimal way to take advantage of all the information available. We demonstrate the strength of this technique using the Hubble Deep Field, where we show that we can extend the detection limit significantly. We also show that this method can identify a significant number of objects that traditional techniques usually can not detect. Finally I propose a new

  8. The void galaxy survey: Star formation properties

    NASA Astrophysics Data System (ADS)

    Beygu, B.; Kreckel, K.; van der Hulst, J. M.; Jarrett, T. H.; Peletier, R.; van de Weygaert, R.; van Gorkom, J. H.; Aragon-Calvo, M. A.

    2016-05-01

    We study the star formation properties of 59 void galaxies as part of the Void Galaxy Survey (VGS). Current star formation rates are derived from H α and recent star formation rates from near-UV imaging. In addition, infrared 3.4, 4.6, 12 and 22 μm Wide-field Infrared Survey Explorer emission is used as star formation and mass indicator. Infrared and optical colours show that the VGS sample displays a wide range of dust and metallicity properties. We combine these measurements with stellar and H I masses to measure the specific SFRs (SFR/M*) and star formation efficiencies ({SFR/{M }_H I}). We compare the star formation properties of our sample with galaxies in the more moderate density regions of the cosmic web, `the field'. We find that specific SFRs of the VGS galaxies as a function of stellar and H I mass are similar to those of the galaxies in these field regions. Their SFR α is slightly elevated than the galaxies in the field for a given total H I mass. In the global star formation picture presented by Kennicutt-Schmidt, VGS galaxies fall into the regime of low average star formation and correspondingly low H I surface density. Their mean {SFR α /{M}_{H I} and SFR α/M* are of the order of 10- 9.9 yr- 1. We conclude that while the large-scale underdense environment must play some role in galaxy formation and growth through accretion, we find that even with respect to other galaxies in the more mildly underdense regions, the increase in star formation rate is only marginal.

  9. THE ACS NEARBY GALAXY SURVEY TREASURY

    SciTech Connect

    Dalcanton, Julianne J.; Williams, Benjamin F.; Rosema, Keith; Gogarten, Stephanie M.; Christensen, Charlotte; Gilbert, Karoline; Hodge, Paul; Seth, Anil C.; Dolphin, Andrew; Holtzman, Jon; Skillman, Evan D.; Weisz, Daniel; Cole, Andrew; Girardi, Leo; Karachentsev, Igor D.; Olsen, Knut; Freeman, Ken; Gallart, Carme; De Jong, Roelof S. E-mail: ben@astro.washington.edu E-mail: stephanie@astro.washington.edu E-mail: fabio@astro.washington.edu E-mail: aseth@cfa.harvard.edu

    2009-07-15

    The ACS Nearby Galaxy Survey Treasury (ANGST) is a systematic survey to establish a legacy of uniform multi-color photometry of resolved stars for a volume-limited sample of nearby galaxies (D < 4 Mpc). The survey volume encompasses 69 galaxies in diverse environments, including close pairs, small and large groups, filaments, and truly isolated regions. The galaxies include a nearly complete range of morphological types spanning a factor of {approx}10{sup 4} in luminosity and star formation rate. The survey data consist of images taken with the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope (HST), supplemented with archival data and new Wide Field Planetary Camera 2 (WFPC2) imaging taken after the failure of ACS. Survey images include wide field tilings covering the full radial extent of each galaxy, and single deep pointings in uncrowded regions of the most massive galaxies in the volume. The new wide field imaging in ANGST reaches median 50% completenesses of m {sub F475W} = 28.0 mag, m {sub F606W} = 27.3 mag, and m {sub F814W} = 27.3 mag, several magnitudes below the tip of the red giant branch (TRGB). The deep fields reach magnitudes sufficient to fully resolve the structure in the red clump. The resulting photometric catalogs are publicly accessible and contain over 34 million photometric measurements of >14 million stars. In this paper we present the details of the sample selection, imaging, data reduction, and the resulting photometric catalogs, along with an analysis of the photometric uncertainties (systematic and random), for both ACS and WFPC2 imaging. We also present uniformly derived relative distances measured from the apparent magnitude of the TRGB.

  10. Studying Dark Energy with Galaxy Cluster Surveys

    NASA Astrophysics Data System (ADS)

    Mohr, J.; Majumdar, S.

    2003-05-01

    Galaxy cluster surveys provide a powerful means of studying the amount and nature of the dark energy. Cluster surveys are complementary to studies using supernova distance estimates, because the cosmological parameter degeneracies are quite different. The redshift distribution of detected clusters in a deep, large solid angle survey is very sensitive to the dark energy equation of state, but robust constraints require mass--observable relations that connect cluster halo mass to observables such as the X-ray luminosity, Sunyaev-Zel'dovich effect distortion, galaxy light or weak lensing shear. Observed regularity in the cluster population and the application of multiple, independent mass estimators provide evidence that these scaling relations exist in the local and intermediate redshift universe. Large cluster surveys contain enough information to study the dark energy and solve for these scaling relations and their evolution with redshift. This self--calibrating nature of galaxy cluster surveys provides a level of robustness that is extremely attractive. Cosmological constraints from a survey can be improved by including more than just the redshift distribution. Limited followup of as few as 1% of the surveyed clusters to make detailed mass measurements improves the cosmological constraints. Including constraints on the mass function at each redshift provides additional power in solving for the evolution of the mass--observable relation. An analysis of the clustering of the surveyed clusters provides additional cosmological discriminating power. There are several planned or proposed cluster surveys that will take place over the next decade. Observational challenges include estimating cluster redshifts and understanding the survey completeness. These challenges vary with wavelength regime, suggesting that multiwavelength surveys provide the most promising avenue for precise galaxy cluster studies of the dark energy. This work is supported in part by the NASA Long

  11. The WFIRST Galaxy Survey Exposure Time Calculator

    NASA Technical Reports Server (NTRS)

    Hirata, Christopher M.; Gehrels, Neil; Kneib, Jean-Paul; Kruk, Jeffrey; Rhodes, Jason; Wang, Yun; Zoubian, Julien

    2013-01-01

    This document describes the exposure time calculator for the Wide-Field Infrared Survey Telescope (WFIRST) high-latitude survey. The calculator works in both imaging and spectroscopic modes. In addition to the standard ETC functions (e.g. background and SN determination), the calculator integrates over the galaxy population and forecasts the density and redshift distribution of galaxy shapes usable for weak lensing (in imaging mode) and the detected emission lines (in spectroscopic mode). The source code is made available for public use.

  12. The Arecibo Galaxy Environment Survey IX: the isolated galaxy sample

    NASA Astrophysics Data System (ADS)

    Minchin, R. F.; Auld, R.; Davies, J. I.; Karachentsev, I. D.; Keenan, O. C.; Momjian, E.; Rodriguez, R.; Taber, T.; Taylor, R.

    2016-02-01

    We have used the Arecibo L-band Feed Array (ALFA) to map three regions, each of 5 deg2, around the isolated galaxies NGC 1156, UGC 2082, and NGC 5523. In the vicinity of these galaxies we have detected two dwarf companions: one near UGC 2082, previously discovered by the Arecibo Legacy Fast ALFA (ALFALFA) survey, and one near NGC 1156, discovered by this project and reported in an earlier paper. This is significantly fewer than the 15.4^{+1.7}_{-1.5} that would be expected from the field H I mass function from ALFALFA or the 8.9 ± 1.2 expected if the H I mass function from the Local Group applied in these regions. The number of dwarf companions detected is, however, consistent with a flat or declining H I mass function as seen by a previous, shallower, H I search for companions to isolated galaxies. We attribute this difference in H I mass functions to the different environments in which they are measured. This agrees with the general observation that lower ratios of dwarf to giant galaxies are found in lower density environments.

  13. Probing Galaxy Formation and Submillimeter Surveys

    NASA Technical Reports Server (NTRS)

    Dwek, Eli; Arendt, Richard G.; Benford, Dominic J.; Moseley, Harvey S.; Shafer, Richard A.; Staguhn, Johannes G.; Fisher, Richard R. (Technical Monitor)

    2002-01-01

    Multiwavelength observations of galaxies have revealed that a significant fraction of the their stellar or accretion luminosity is absorbed and reradiated by dust at far-infrared (FIR) and submillimeter (submm) wavelengths. Submillimeter (850 micron) surveys conducted by the SCUBA instrument on the JCMT have detected a population of high redshift (z approximately equal to 1-4) ultraluminous infrared galaxies, that dominate the luminosity densities at those redshifts. Their cumulative contribution to the cosmic infrared background (CIB) detected by the COBE satellite is comparable to the observations, suggesting that at 850 microns the CIB is resolved into its constituent sources. This suggests that the early universe was much more dust enshrouded than the present one. FIR and submm surveys can therefore address fundamental questions regarding the early processes of galaxy formation and their evolution in number and luminosity over cosmic history. The scientific information that can be obtained from such surveys depend on a number of parameters, the most important of which are the diameter of the telescope and the wavelengths of the survey. We summarize the effect of these parameters on the scientific return from such surveys.

  14. Constraining inflation with future galaxy redshift surveys

    SciTech Connect

    Huang, Zhiqi; Vernizzi, Filippo; Verde, Licia E-mail: liciaverde@icc.ub.edu

    2012-04-01

    With future galaxy surveys, a huge number of Fourier modes of the distribution of the large scale structures in the Universe will become available. These modes are complementary to those of the CMB and can be used to set constraints on models of the early universe, such as inflation. Using a MCMC analysis, we compare the power of the CMB with that of the combination of CMB and galaxy survey data, to constrain the power spectrum of primordial fluctuations generated during inflation. We base our analysis on the Planck satellite and a spectroscopic redshift survey with configuration parameters close to those of the Euclid mission as examples. We first consider models of slow-roll inflation, and show that the inclusion of large scale structure data improves the constraints by nearly halving the error bars on the scalar spectral index and its running. If we attempt to reconstruct the inflationary single-field potential, a similar conclusion can be reached on the parameters characterizing the potential. We then study models with features in the power spectrum. In particular, we consider ringing features produced by a break in the potential and oscillations such as in axion monodromy. Adding large scale structures improves the constraints on features by more than a factor of two. In axion monodromy we show that there are oscillations with small amplitude and frequency in momentum space that are undetected by CMB alone but can be measured by including galaxy surveys in the analysis.

  15. Combining galaxy and 21-cm surveys

    NASA Astrophysics Data System (ADS)

    Cohn, J. D.; White, Martin; Chang, Tzu-Ching; Holder, Gil; Padmanabhan, Nikhil; Doré, Olivier

    2016-04-01

    Acoustic waves travelling through the early Universe imprint a characteristic scale in the clustering of galaxies, QSOs and intergalactic gas. This scale can be used as a standard ruler to map the expansion history of the Universe, a technique known as baryon acoustic oscillations (BAO). BAO offer a high-precision, low-systematics means of constraining our cosmological model. The statistical power of BAO measurements can be improved if the `smearing' of the acoustic feature by non-linear structure formation is undone in a process known as reconstruction. In this paper, we use low-order Lagrangian perturbation theory to study the ability of 21-cm experiments to perform reconstruction and how augmenting these surveys with galaxy redshift surveys at relatively low number densities can improve performance. We find that the critical number density which must be achieved in order to benefit 21-cm surveys is set by the linear theory power spectrum near its peak, and corresponds to densities achievable by upcoming surveys of emission line galaxies such as eBOSS and DESI. As part of this work, we analyse reconstruction within the framework of Lagrangian perturbation theory with local Lagrangian bias, redshift-space distortions, {k}-dependent noise and anisotropic filtering schemes.

  16. Field Galaxy Evolution with the MUNICS Survey

    NASA Astrophysics Data System (ADS)

    Drory, Niv; Feulner, Georg; Hopp, Ulrich; Snigula, Jan; Bender, Ralf

    The Munich Near-IR Cluster Survey (MUNICS) is a K'-selected survey uniformly covering 1 square degree in the J and K' near-IR bands. The survey area consists of 8 13.2 × 26.2 arcmin randomly selected fields at high galactic latitude, as well as 13 7 × 7 arcmin fields targeted towards 0.6 < z <1.5 QSOs. The 3 σ detection limits for a point source are 19.5 in the K'-band and 21.5 in the J-band. The data have been acquired at the 3.5m telescope at Calar Alto Observatory using the Ω - Prime camera. Optical photometry in the V, R, and I bands was obtained for a subsample of the survey fields covering 0.35 square degrees in total. These data have been obtained at the 2.2m telescope at Calar Alto Observatory and the 2.7m telescope at McDonald Observatory. These data enable us to determine photometric redshifts for the galaxies and thus are of great importance in selecting and confirming cluster candidates as well as individual galaxies for follow-up spectroscopy. The project has two main scientific aims, namely - the identification of galaxy clusters at redshifts around unity, and - the selection of a fair sample of field early-type galaxies at similar redshifts for evolutionary studies. Near-IR selection is an efficient tool for tracing the massive galaxy population at redshifts around unity because of its high sensitivity for evolved stellar populations even in the presence of moderate star formation activity. The formation and evolution of the population of massive galaxies is still a matter of lively and controversial debate. While models of hierarchical galaxy formation consistently predict a steep decline in the number density of massive spheroidals, they have a rather large number of free parameters, some of which involve ill-understood processes. Observation has not yet been successful in constraining the ranges of the involved model parameters tightly enough, so that comparisons between theory and experiment are difficult to interpret.

  17. Probing primordial features with future galaxy surveys

    NASA Astrophysics Data System (ADS)

    Ballardini, M.; Finelli, F.; Fedeli, C.; Moscardini, L.

    2016-10-01

    We study the capability of future measurements of the galaxy clustering power spectrum to probe departures from a power-law spectrum for primordial fluctuations. On considering the information from the galaxy clustering power spectrum up to quasi-linear scales, i.e. k < 0.1 h Mpc‑1, we present forecasts for DESI, Euclid and SPHEREx in combination with CMB measurements. As examples of departures in the primordial power spectrum from a simple power-law, we consider four Planck 2015 best-fits motivated by inflationary models with different breaking of the slow-roll approximation. At present, these four representative models provide an improved fit to CMB temperature anisotropies, although not at statistical significant level. As for other extensions in the matter content of the simplest ΛCDM model, the complementarity of the information in the resulting matter power spectrum expected from these galaxy surveys and in the primordial power spectrum from CMB anisotropies can be effective in constraining cosmological models. We find that the three galaxy surveys can add significant information to CMB to better constrain the extra parameters of the four models considered.

  18. WINGS: WFIRST Infrared Nearby Galaxy Survey

    NASA Astrophysics Data System (ADS)

    Williams, Benjamin

    testing and optimizing WFIRST observing strategies and providing science guidance to trade studies of observatory requirements such as field of view, pixel scale and filter selection. First, we will perform extensive simulations of galaxies' halo substructures and stellar populations that will be used as input for optimizing observing strategies and sample selection. Second, we will develop a pipeline that optimizes stellar photometry, proper motion, and variability measurements with WFIRST. This software will: maximize data quality & scientific yield; provide essential, independent calibrations to the larger WFIRST efforts; and rapidly provide accurate photometry and astrometry to the community. Third, we will derive quantitative performance metrics to fairly evaluate trade-offs between different survey strategies and WFIRST performance capabilities. The end result of this effort will be: (1) an efficient survey strategy that maximizes the scientific yield of what would otherwise be a chaotic archive of observations from small, un-coordinated programs; (2) a suite of analysis tools and a state-of-the-art pipeline that can be deployed after launch to rapidly deliver stellar photometry to the public; (3) a platform to independently verify the calibration and point spread function modeling that are essential to the primary WFIRST goals, but that are best tested from images of stellar populations. These activities will be carried out by a Science Investigation Team that has decades of experience in using nearby galaxies to inform fundamental topics in astrophysics. This team is composed of researchers who have led the charge in observational and theoretical studies of resolved stellar populations and stellar halos. With our combined background, we are poised to take full advantage of the large field of view and high spatial resolution WFIRST will offer.

  19. The ISO-IRAS Faint Galaxy Survey

    NASA Technical Reports Server (NTRS)

    Smith, Harding E.

    1999-01-01

    As part of the ISO-IRAS Faint Galaxy Survey ISO Satellite observations of over 600 IRAS sources have been obtained with the ISOCAM instrument. Because our survey strategy involved relatively short integrations, great care was required in developing analysis software including cosmic-ray and transient removal and calibration. These observations have now been through final pipeline processing at IPAC and ground-based follow-up is ongoing. The observations are for sources from two samples: a " Filler' sample selected to be at z greater than 0.1 and a fainter sample which selected for the highest redshift galaxies in the IRAS survey, with redshifts 0.2 less than z less than 1.0. I now have obtained ground-based follow-up spectrophotometry at Lick and Palomar observatories for 100 LFIRGs with 0.1 less than z less than 0.7. Our observations have confirmed that these systems are comparable to nearby LFIRGs such as Arp 220, with L (sub -)(fir) greater than 10(exp 11) L(sub -) sun and typically HII/Liner optical excitation. About 10% of the galaxies show true AGN (Sy2) excitation. Based on our work on a nearby complete sample of LFIRGS, we believe that the majority of these systems are luminous Starbursts, thus this project is tracing the luminous end of the galaxy star-forming luminosity function - the (infrared) star-formation history of the Universe to z approx. 1, a topic of some considerable recent interest. A by-product of these ISOCAM observations is approximately 1 square degree of deep 2 microns pointings outside the IRAS error boxes, allowing us an independent estimate of the mid-infrared log N - log S relation. Ground-based observations of this sample are continuing.

  20. Understanding cosmic acceleration with galaxy redshift surveys

    NASA Astrophysics Data System (ADS)

    Guzzo, L.

    Our increased efficiency in performing massive redshift surveys of galaxies well beyond the local Universe (i.e. z≫ 0.1) is opening up new possibilities to understanding the observed acceleration of cosmic expansion, the greatest mystery in modern cosmology. Redshift surveys can measure both the expansion history H(z) and the evolution of the growth rate of structure f(z). Coupling these two measurements one can distinguish wether cosmic acceleration is due to a new form of ``dark energy'' in the cosmic budget, or rather requires a modification of General Relativity. These two radically alternative scenarios are degenerate when considering H(z) alone, as yielded, e.g., by the Hubble diagram of Type Ia supernovae. While redshift surveys have the ability to measure H(z) through Baryonic Acoustic Oscillations in the galaxy power spectrum, they can at the same time probe f(z) using the redshift-space distortions introduced in the observed clustering pattern by galaxy peculiar motions. In this short review paper I will mostly concentrate on the latter measurement, whose potential importance in this context has been recently highlighted \\citep{guz08}. Current estimates are consistent with the simplest cosmological-constant scenario, but error bars are still too large to rule out alternative models. Extensive simulations show that with the next-generation deep surveys with N>100,000 redshifts over large (>20 deg2) areas, redshift distortions can be one of the key tools for understanding the physical origin of cosmic acceleration.

  1. The Void Galaxy Survey: Morphology and Star Formation Properties of Void Galaxies

    NASA Astrophysics Data System (ADS)

    Beygu, Burcu; Kreckel, Kathryn; van der Hulst, Thijs; Peletier, Reynier; Jarrett, Tom; van de Weygaert, Rien; van Gorkom, Jacqueline H.; Aragón-Calvo, Miguel

    2016-10-01

    We present the structural and star formation properties of 59 void galaxies as part of the Void Galaxy Survey (VGS). Our aim is to study in detail the physical properties of these void galaxies and study the effect of the void environment on galaxy properties. We use Spitzer 3.6μ and B-band imaging to study the morphology and color of the VGS galaxies. For their star formation properties, we use Hα and GALEX near-UV imaging. We compare our results to a range of galaxies of different morphologies in higher density environments. We find that the VGS galaxies are in general disk dominated and star forming galaxies. Their star formation rates are, however, often less than 1 M⊙ yr-1. There are two early-type galaxies in our sample as well. In re versus MB parameter space, VGS galaxies occupy the same space as dwarf irregulars and spirals.

  2. Exploring dark matter microphysics with galaxy surveys

    SciTech Connect

    Escudero, Miguel; Mena, Olga; Vincent, Aaron C.; Wilkinson, Ryan J.; Boehm, Céline E-mail: omena@ific.uv.es E-mail: ryan.wilkinson@durham.ac.uk

    2015-09-01

    We use present cosmological observations and forecasts of future experiments to illustrate the power of large-scale structure (LSS) surveys in probing dark matter (DM) microphysics and unveiling potential deviations from the standard ΛCDM scenario. To quantify this statement, we focus on an extension of ΛCDM with DM-neutrino scattering, which leaves a distinctive imprint on the angular and matter power spectra. After finding that future CMB experiments (such as COrE+) will not significantly improve the constraints set by the Planck satellite, we show that the next generation of galaxy clustering surveys (such as DESI) could play a leading role in constraining alternative cosmologies and even have the potential to make a discovery. Typically we find that DESI would be an order of magnitude more sensitive to DM interactions than Planck, thus probing effects that until now have only been accessible via N-body simulations.

  3. A systematic survey for distant galaxy clusters

    NASA Technical Reports Server (NTRS)

    Gunn, J. E.; Hoessel, J. G.; Oke, J. B.

    1986-01-01

    A photographic survey for faint clusters of galaxies has been carried out with fine-grained photographic emulsions using the 1.2 m Schmidt and 5 m Hale telescopes, as well as the 4 m Mayall telescope. A total of 418 clusters have been found with redshifts mostly in the range from 0.15 to 0.92. The survey was planned to minimize distance-dependent selection effects in the resulting catalog. In areas of sky where the deepest search was made, the sample is complete to about z = 0.50; there are 11 clusters per square degree at this limit. At a redshift of 1.0 there should be 63 or 45 clusters per square degree depending on whether q0 is 0.0 or 0.5, provided there is no evolution.

  4. The SAMI Galaxy Survey: instrument specification and target selection

    NASA Astrophysics Data System (ADS)

    Bryant, J. J.; Owers, M. S.; Robotham, A. S. G.; Croom, S. M.; Driver, S. P.; Drinkwater, M. J.; Lorente, N. P. F.; Cortese, L.; Scott, N.; Colless, M.; Schaefer, A.; Taylor, E. N.; Konstantopoulos, I. S.; Allen, J. T.; Baldry, I.; Barnes, L.; Bauer, A. E.; Bland-Hawthorn, J.; Bloom, J. V.; Brooks, A. M.; Brough, S.; Cecil, G.; Couch, W.; Croton, D.; Davies, R.; Ellis, S.; Fogarty, L. M. R.; Foster, C.; Glazebrook, K.; Goodwin, M.; Green, A.; Gunawardhana, M. L.; Hampton, E.; Ho, I.-T.; Hopkins, A. M.; Kewley, L.; Lawrence, J. S.; Leon-Saval, S. G.; Leslie, S.; McElroy, R.; Lewis, G.; Liske, J.; López-Sánchez, Á. R.; Mahajan, S.; Medling, A. M.; Metcalfe, N.; Meyer, M.; Mould, J.; Obreschkow, D.; O'Toole, S.; Pracy, M.; Richards, S. N.; Shanks, T.; Sharp, R.; Sweet, S. M.; Thomas, A. D.; Tonini, C.; Walcher, C. J.

    2015-03-01

    The SAMI Galaxy Survey will observe 3400 galaxies with the Sydney-AAO Multi-object Integral-field spectrograph (SAMI) on the Anglo-Australian Telescope in a 3-yr survey which began in 2013. We present the throughput of the SAMI system, the science basis and specifications for the target selection, the survey observation plan and the combined properties of the selected galaxies. The survey includes four volume-limited galaxy samples based on cuts in a proxy for stellar mass, along with low-stellar-mass dwarf galaxies all selected from the Galaxy And Mass Assembly (GAMA) survey. The GAMA regions were selected because of the vast array of ancillary data available, including ultraviolet through to radio bands. These fields are on the celestial equator at 9, 12 and 14.5 h, and cover a total of 144 deg2 (in GAMA-I). Higher density environments are also included with the addition of eight clusters. The clusters have spectroscopy from 2-degree Field Galaxy Redshift Survey (2dFGRS) and Sloan Digital Sky Survey (SDSS) and photometry in regions covered by the SDSS and/or VLT Survey Telescope/ATLAS. The aim is to cover a broad range in stellar mass and environment, and therefore the primary survey targets cover redshifts 0.004 < z < 0.095, magnitudes rpet < 19.4, stellar masses 107-1012 M⊙, and environments from isolated field galaxies through groups to clusters of ˜1015 M⊙.

  5. First Results from the ISO-IRAS Faint Galaxy Survey

    NASA Technical Reports Server (NTRS)

    Wolstencroft, R. D.; Wehrle, A. E.; Levine, D. A.

    1997-01-01

    We present the first result from the ISO-IRAS Faint Galaxy Survey (IIFGS), a program designed to obtain ISO observations of the most distant and luminous galaxies in the IRAS Faint Source Survey by filling short gaps in the ISO observing schedule with pairs of 12um ISOCAM AND 90um ISOPHOT observation.

  6. THE GALAXY OPTICAL LUMINOSITY FUNCTION FROM THE AGN AND GALAXY EVOLUTION SURVEY

    SciTech Connect

    Cool, Richard J.; Eisenstein, Daniel J.; Kochanek, Christopher S.; Brown, Michael J. I.; Caldwell, Nelson; Forman, William R.; Hickox, Ryan C.; Jones, Christine; Murray, Stephen S.; Dey, Arjun; Jannuzi, Buell T.; Moustakas, John

    2012-03-20

    We present the galaxy optical luminosity function for the redshift range 0.05 < z < 0.75 from the AGN and Galaxy Evolution Survey, a spectroscopic survey of 7.6 deg{sup 2} in the Booetes field of the NOAO Deep Wide-Field Survey. Our statistical sample is composed of 12,473 galaxies with known redshifts down to I = 20.4 (AB). Our results at low redshift are consistent with those from Sloan Digital Sky Survey; at higher redshift, we find strong evidence for evolution in the luminosity function, including differential evolution between blue and red galaxies. We find that the luminosity density evolves as (1 + z){sup (0.54{+-}0.64)} for red galaxies and (1 + z){sup (1.64{+-}0.39)} for blue galaxies.

  7. Structural decomposition of galaxies in the CALIFA survey

    NASA Astrophysics Data System (ADS)

    Kuutma, Teet; Tamm, Antti; Tempel, Elmo

    2016-10-01

    Several clues for understanding the nature and evolution of galaxies can be gained by studying galactic structures and their evolution with time and environment. However, even for nearby galaxies, detailed structural decomposition is not a straightforward task. Choosing the number of structural components and the limits placed on their parameters can have a large effect on the derived characteristics of galaxies. For distant galaxies, structural analysis is further hampered by the spatial resolution limits of the imaging. However, by using a relatively robust two-component bulge+disk modelling, galaxies in the nearby Universe can be compared to distant galaxies for tracing signs of evolution in the extracted structures. We start such a study by analysing first a well observed nearby sample of galaxies, using ~600 targets from the CALIFA survey. We show that even in this small sample of nearby galaxies, the effects of environmental density are already well apparent.

  8. A CO Survey of the Southern Galaxy

    NASA Astrophysics Data System (ADS)

    Bronfman, L.; May, J.; Luna, A.

    On December 12th 1982 the 1.2 mSouthern Millimeter Wave Telescope, an instrument specifically designed for CO surveys of molecular clouds in the Southern Galaxy, arrived Cerro Tololo after being constructed and tested atop the roof of the Goddard Institute for Space Studies by Columbia University staff and students, and by Universidad de Chile and NASA personnel. The telescope saw first light on December 22nd 1982, and has been operational ever since. During these years we have completed deep CO surveys of the Carina arm (Grabelsky et al. 1987), the IV galactic quadrant (Bronfman et al. 1988), the III galactic quadrant (May et al. 1993), and the galactic center (Bitran et al. 1997), contributing with a major fraction of the presently available galactic CO data. When combined with CO surveys of the I and II galactic quadrants obtained with its twin instrument, the Northern 1.2m Millimeter Wave Telescope now at the Center for Astrophysics, these data provided for the first time a complete, well sampled, and homogeneous picture of the molecular gas content of the Milky Way.

  9. A Survey of nearby, nearly face-on spiral galaxies

    NASA Astrophysics Data System (ADS)

    Garmire, Gordon

    2014-09-01

    This is a continuation of a survey of nearby, nearly face-on spiral galaxies. The main purpose is to search for evidence of collisions with small galaxies that show up in X-rays by the generation of hot shocked gas from the collision. Secondary objectives include study of the spatial distribution point sources in the galaxy and to detect evidence for a central massive blackhole. These are alternate targets.

  10. A Survey of nearby, nearly face-on spiral galaxies

    NASA Astrophysics Data System (ADS)

    Garmire, Gordon

    2014-09-01

    This is a continuation of a survey of nearby, nearly face-on spiral galaxies. The main purpose is to search for evidence of collisions with small galaxies that show up in X-rays by the generation of hot shocked gas from the collision. Secondary objectives include study of the spatial distribution point sources in the galaxy and to detect evidence for a central massive blackhole.

  11. ChaMP Serendipitous Galaxy Cluster Survey

    SciTech Connect

    Barkhouse, Wayne A.; Green, P.J.; Vikhlinin, A.; Kim, D.-W.; Perley, D.; Cameron, R.; Silverman, J.; Mossman, A.; Burenin, R.; Jannuzi, B.T.; Kim, M.; Smith, M.G.; Smith, R.C.; Tananbaum, H.; Wilkes, B.J.; /Harvard-Smithsonian Ctr. Astrophys. /UC, Berkeley, Astron. Dept. /SLAC /Garching, Max Planck Inst., MPE /Moscow, Space Res. Inst. /NOAO, Tucson /Cerro-Tololo InterAmerican Obs.

    2006-04-03

    We present a survey of serendipitous extended X-ray sources and optical cluster candidates from the Chandra Multi-wavelength Project (ChaMP). Our main goal is to make an unbiased comparison of X-ray and optical cluster detection methods. In 130 archival Chandra pointings covering 13 square degrees, we use a wavelet decomposition technique to detect 55 extended sources, of which 6 are nearby single galaxies. Our X-ray cluster catalog reaches a typical flux limit of about {approx} 10{sup -14} erg s{sup -1} cm{sup -2}, with a median cluster core radius of 21''. For 56 of the 130 X-ray fields, we use the ChaMP's deep NOAO/4m MOSAIC g', r', and i' imaging to independently detect cluster candidates using a Voronoi tessellation and percolation (VTP) method. Red-sequence filtering decreases the galaxy fore/background contamination and provides photometric redshifts to z {approx} 0.7. From the overlapping 6.1 square degree X-ray/optical imaging, we find 115 optical clusters (of which 11% are in the X-ray catalog) and 28 X-ray clusters (of which 46% are in the optical VTP catalog). The median redshift of the 13 X-ray/optical clusters is 0.41, and their median X-ray luminosity (0.5-2 keV) is L{sub X} = (2.65 {+-} 0.19) x 10{sup 43} ergs s{sup -1}. The clusters in our sample that are only detected in our optical data are poorer on average ({approx} 4{sigma}) than the X-ray/optically matched clusters, which may partially explain the difference in the detection fractions.

  12. Galaxy morphologies in the era of big-data surveys

    NASA Astrophysics Data System (ADS)

    Huertas-Company, M.

    Galaxy morphology is a first-order descriptor of a galaxy and a useful proxy to identify physical processes. The 100 years old Hubble fork describes the structural diversity of galaxies in the local universe. Unveiling the origins of this galaxy zoology is a key challenge in galaxy evolution. In this review talk, I first summarized some key advances in our understanding of the morphological evolution of galaxies from z ~ 0 to z ~ 3, thank you in particular to the SDSS and HST legacies. In the second part, I focused on the classification techniques. With the emergence in the last years of large surveys the samples of study have increased by several orders of magnitude going from a few tens to several millions of objects. This trend will clearly continue in the next decade with coming surveys/missions such as EUCLID and WFIRST. While galaxy classification is still a required step in any survey, visual inspection of galaxies is becoming prohibitively time-consuming. Under these circumstances, the techniques used to estimate galaxy morphologies need to be updated.

  13. Galaxy Evolution Within the Kilo-Degree Survey

    NASA Astrophysics Data System (ADS)

    Tortora, C.; Napolitano, N. R.; La Barbera, F.; Roy, N.; Radovich, M.; Getman, F.; Brescia, M.; Cavuoti, S.; Capaccioli, M.; Longo, G.

    The ESO Public Kilo-Degree Survey (KiDS) is an optical wide-field imaging survey carried out with the VLT Survey Telescope and the OmegaCAM camera. KiDS will scan 1,500 deg2 in four optical filters (u, g, r, i). Designed to be a weak lensing survey, it is ideal for galaxy evolution studies, thanks to the high spatial resolution of VST, the excellent seeing and the photometric depth. The surface photometry has provided with structural parameters (e.g. size and Sérsic index), aperture and total magnitudes have been used to obtain photometric redshifts from Machine Learning methods and stellar masses/luminositites from stellar population synthesis. Our project aimed at investigating the evolution of the colour and structural properties of galaxies with mass and environment up to redshift z ˜ 0.5 and more, to put constraints on galaxy evolution processes, as galaxy mergers.

  14. Ultraluminous infrared galaxies in the AKARI all-sky survey

    SciTech Connect

    Kilerci Eser, E.; Goto, T.; Doi, Y. E-mail: doi@ea.c.u-tokyo.ac.jp

    2014-12-10

    We present a new catalog of 118 ultraluminous infrared galaxies (ULIRGs) and one hyperluminous infrared galaxy (HLIRG) by cross-matching the AKARI all-sky survey with the Sloan Digital Sky Survey Data Release 10 (SDSS DR10) and the final data release of the Two-Degree Field Galaxy Redshift Survey. Forty of the ULIRGs and one HLIRG are new identifications. We find that ULIRGs are interacting pair galaxies or ongoing or postmergers. This is consistent with the widely accepted view: ULIRGs are major mergers of disk galaxies. We confirm the previously known positive trend between the active galactic nucleus fraction and infrared luminosity. We show that ULIRGs have a large offset from the main sequence up to z ∼ 1; their offset from the z ∼ 2 'main sequence' is relatively smaller. We find a result consistent with the previous studies showing that, compared to local star-forming SDSS galaxies of similar mass, local ULIRGs have lower oxygen abundances. We demonstrate for the first time that ULIRGs follow the fundamental metallicity relation (FMR). The scatter of ULIRGs around the FMR (0.09 dex-0.5 dex) is comparable to the scatter of z ∼ 2-3 galaxies. We provide the largest local (0.050

  15. The Void Galaxy Survey: photometry, structure and identity of void galaxies

    NASA Astrophysics Data System (ADS)

    Beygu, B.; Peletier, R. F.; van der Hulst, J. M.; Jarrett, T. H.; Kreckel, K.; van de Weygaert, R.; van Gorkom, J. H.; Aragon-Calvo, M. A.

    2016-09-01

    We analyze photometry from deep B-band images of 59 void galaxies in the Void Galaxy Survey (VGS), together with their near-infrared 3.6μm and 4.5μm Spitzer photometry. The VGS galaxies constitute a sample of void galaxies that were selected by a geometric-topological procedure from the SDSS DR7 data release, and which populate the deep interior of voids. Our void galaxies span a range of absolute B-magnitude from {M_B=-15.5} to {M_B=-20}, while at the 3.6μm band their magnitudes range from {M_{3.6}=-18} to {M_{3.6}=-24}. Their B-[3.6] colour and structural parameters indicate these are star forming galaxies. A good reflection of the old stellar population, the near-infrared band photometry also provide a robust estimate of the stellar mass, which for the VGS galaxies we confirm to be smaller than 3 × 1010 M⊙. In terms of the structural parameters and morphology, our findings align with other studies in that our VGS galaxy sample consists mostly of small late-type galaxies. Most of them are similar to Sd-Sm galaxies, although a few are irregularly shaped galaxies. The sample even includes two early-type galaxies, one of which is an AGN. Their Sérsic indices are nearly all smaller than n = 2 in both bands and they also have small half-light radii. In all, we conclude that the principal impact of the void environment on the galaxies populating them mostly concerns their low stellar mass and small size.

  16. Massive Quiescent Disk Galaxies in the CANDELS survey

    NASA Astrophysics Data System (ADS)

    Kesseli, Aurora; McGrath, E. J.; CANDELS Collaboration

    2014-01-01

    Using data from the GOODS-S field of the CANDELS survey, we find evidence for an increasing fraction of disk-dominated galaxies at high-redshift ( 2) among the quiescent, or non-star-forming galaxy population, in agreement with a growing body of evidence from recent results in the literature. We selected all galaxies with mass M>1010 Msun within the redshift range 0.5 ≤ z ≤ 2.5, and imposed a two-color selection criteria using rest-frame U, V, and J-band flux to separate quiescent from star-forming galaxies. From this sample, we performed a qualitative visual classification and a quantitative classification using the galaxy-fitting program Galfit. Of the original 140 quiescent galaxies, 23 have a disk component that contributes 50% or more of the total integrated galaxy light, and most of these are at high-redshift. At a redshift of z ~ 2 a significant fraction of all quiescent galaxies showed strong disk components with 30% being disk-dominated. We also find that massive disk galaxies seem to live in less densely populated environments while massive ellipticals live in environments with more neighbors, which leads us to believe that there are two mechanisms for the creation of massive quiescent galaxies. For the disks, the lower density environment and the disk nature of these galaxies lead us to favor cold streams over the major merger model of galaxy formation. The ellipticals, which live in higher density environments, could be assembled through major mergers of already aged stellar populations (e.g., dry mergers). This research is supported by the Clare Boothe Luce Foundation.

  17. CORRELATIONS AMONG GALAXY PROPERTIES FROM THE SLOAN DIGITAL SKY SURVEY

    SciTech Connect

    Li Zhongmu; Mao Caiyan

    2013-07-01

    Galaxies are complex systems with many properties. Correlations among galaxy properties can supply important clues for studying the formation and evolution of galaxies. Using principal component analysis and least-squares fitting, this paper investigates the correlations among galactic parameters involving more properties (color, morphology, stellar population, and absolute magnitude) than previous studies. We use a volume-limited sample (whole sample) of 75,423 galaxies that was selected from the Sloan Digital Sky Survey Data Release 2 and divided into two subsamples (blue and red samples) using a critical color of (g - r) = 0.70 mag. In addition to recovering some previous results, we also obtain some new results. First, all separators for dividing galaxies into two groups can be related via good parameter-first principal component (PC1) correlations. A critical PC1 that indicates whether or not stellar age (or the evolution of a stellar population over time) is important can be used to separate galaxies. This suggests that a statistical parameter, PC1, is helpful in understanding the physical separators of galaxies. In addition, stellar age is shown to be unimportant for red galaxies, while both stellar age and mass are dominating parameters of blue galaxies. This suggests that the various numbers of dominating parameters of galaxies may result from the use of different samples. Finally, some parameters are shown to be correlated, and quantitative fits for a few correlations are obtained, e.g., log(t) = 8.57 + 1.65 (g - r) for the age (log t) and color (g - r) of blue galaxies and log (M{sub *}) = 4.31 - 0.30 M{sub r} for the stellar mass (log M{sub *}) and absolute magnitude (M{sub r}) of red galaxies. The median relationships between various parameter pairs are also presented for comparison.

  18. Adaptive density estimator for galaxy surveys

    NASA Astrophysics Data System (ADS)

    Saar, Enn

    2016-10-01

    Galaxy number or luminosity density serves as a basis for many structure classification algorithms. Several methods are used to estimate this density. Among them kernel methods have probably the best statistical properties and allow also to estimate the local sample errors of the estimate. We introduce a kernel density estimator with an adaptive data-driven anisotropic kernel, describe its properties and demonstrate the wealth of additional information it gives us about the local properties of the galaxy distribution.

  19. Galaxy clustering with photometric surveys using PDF redshift information

    NASA Astrophysics Data System (ADS)

    Asorey, J.; Carrasco Kind, M.; Sevilla-Noarbe, I.; Brunner, R. J.; Thaler, J.

    2016-06-01

    Photometric surveys produce large-area maps of the galaxy distribution, but with less accurate redshift information than is obtained from spectroscopic methods. Modern photometric redshift (photo-z) algorithms use galaxy magnitudes, or colours, that are obtained through multiband imaging to produce a probability density function (PDF) for each galaxy in the map. We used simulated data to study the effect of using different photo-z estimators to assign galaxies to redshift bins in order to compare their effects on angular clustering and galaxy bias measurements. We found that if we use the entire PDF, rather than a single-point (mean or mode) estimate, the deviations are less biased, especially when using narrow redshift bins. When the redshift bin widths are Δz = 0.1, the use of the entire PDF reduces the typical measurement bias from 5 per cent, when using single point estimates, to 3 per cent.

  20. Galaxy clustering with photometric surveys using PDF redshift information

    DOE PAGES

    Asorey, J.; Carrasco Kind, M.; Sevilla-Noarbe, I.; Brunner, R. J.; Thaler, J.

    2016-03-28

    Here, photometric surveys produce large-area maps of the galaxy distribution, but with less accurate redshift information than is obtained from spectroscopic methods. Modern photometric redshift (photo-z) algorithms use galaxy magnitudes, or colors, that are obtained through multi-band imaging to produce a probability density function (PDF) for each galaxy in the map. We used simulated data to study the effect of using different photo-z estimators to assign galaxies to redshift bins in order to compare their effects on angular clustering and galaxy bias measurements. We found that if we use the entire PDF, rather than a single-point (mean or mode) estimate, the deviations are less biased, especially when using narrow redshift bins. When the redshift bin widths aremore » $$\\Delta z=0.1$$, the use of the entire PDF reduces the typical measurement bias from 5%, when using single point estimates, to 3%.« less

  1. SPATIAL ANISOTROPY OF GALAXY KINEMATICS IN SLOAN DIGITAL SKY SURVEY GALAXY CLUSTERS

    SciTech Connect

    Skielboe, Andreas; Wojtak, Radoslaw; Pedersen, Kristian; Rozo, Eduardo; Rykoff, Eli S.

    2012-10-10

    Measurements of galaxy cluster kinematics are important in understanding the dynamical state and evolution of clusters of galaxies, as well as constraining cosmological models. While it is well established that clusters exhibit non-spherical geometries, evident in the distribution of galaxies on the sky, azimuthal variations of galaxy kinematics within clusters have yet to be observed. Here we measure the azimuthal dependence of the line-of-sight velocity dispersion profile in a stacked sample of 1743 galaxy clusters from the Sloan Digital Sky Survey (SDSS). The clusters are drawn from the SDSS DR8 redMaPPer catalog. We find that the line-of-sight velocity dispersion of galaxies lying along the major axis of the central galaxy is larger than those that lie along the minor axis. This is the first observational detection of anisotropic kinematics of galaxies in clusters. We show that the result is consistent with predictions from numerical simulations. Furthermore, we find that the degree of projected anisotropy is strongly dependent on the line-of-sight orientation of the galaxy cluster, opening new possibilities for assessing systematics in optical cluster finding.

  2. Normal and Starburst Galaxies in Deep X-ray Surveys

    NASA Technical Reports Server (NTRS)

    Hornschemeier, Ann

    2006-01-01

    This talk will cover progress of the last several years in unraveling the nature of normal and starburst galaxies in deep X-ray surveys. This includes discussion of the normal galaxy X-ray Luminosity Function in deep field and cluster surveys and what it tells us about the binary populations in galaxies. The utility of broad band X-ray emission, especially as compared to other multiwavelength measurements of current/recent star formation, will be reviewed. These broad band X-ray measurements of star formation are based upon X-ray/Star Formation Rate correlations that span the currently available redshift range (0 < z < 1). I will also discuss new efforts underway to systematically characterize the X-ray emission from galaxies in group and cluster environments, including a new effort underway in the Coma cluster of galaxies. I will finish with discussion of the redshift frontier for studies of X-ray star formation, currently 2 approx.4, where the UV-selected Lyman Break galaxies are the best glimpse we have into X-ray emission from star formation in the early Universe. Lyman Break galaxies are of particular interest due to the overlap in basic properties with starburst galaxies in the more local Universe. Understanding the outflows in such starburst galaxies is of critical importance to constraining the "stellar" portion of cosmic feedback. The talk will close with a brief discussion of distant normal galaxy science with future X-ray observatories such as the upcoming Con-X/XEUS mission(s).

  3. Measuring neutrino masses with a future galaxy survey

    SciTech Connect

    Hamann, Jan; Hannestad, Steen; Wong, Yvonne Y.Y. E-mail: sth@phys.au.dk

    2012-11-01

    We perform a detailed forecast on how well a EUCLID-like photometric galaxy and cosmic shear survey will be able to constrain the absolute neutrino mass scale. Adopting conservative assumptions about the survey specifications and assuming complete ignorance of the galaxy bias, we estimate that the minimum mass sum of Σm{sub ν} ≅ 0.06 eV in the normal hierarchy can be detected at 1.5σ to 2.5σ significance, depending on the model complexity, using a combination of galaxy and cosmic shear power spectrum measurements in conjunction with CMB temperature and polarisation observations from PLANCK. With better knowledge of the galaxy bias, the significance of the detection could potentially reach 5.4σ. Interestingly, neither PLANCK+shear nor PLANCK+galaxy alone can achieve this level of sensitivity; it is the combined effect of galaxy and cosmic shear power spectrum measurements that breaks the persistent degeneracies between the neutrino mass, the physical matter density, and the Hubble parameter. Notwithstanding this remarkable sensitivity to Σm{sub ν}, EUCLID-like shear and galaxy data will not be sensitive to the exact mass spectrum of the neutrino sector; no significant bias ( < 1σ) in the parameter estimation is induced by fitting inaccurate models of the neutrino mass splittings to the mock data, nor does the goodness-of-fit of these models suffer any significant degradation relative to the true one (Δχ{sub eff}{sup 2} < 1)

  4. Hierarchical Bayesian inference of galaxy redshift distributions from photometric surveys

    NASA Astrophysics Data System (ADS)

    Leistedt, Boris; Mortlock, Daniel J.; Peiris, Hiranya V.

    2016-08-01

    Accurately characterizing the redshift distributions of galaxies is essential for analysing deep photometric surveys and testing cosmological models. We present a technique to simultaneously infer redshift distributions and individual redshifts from photometric galaxy catalogues. Our model constructs a piecewise constant representation (effectively a histogram) of the distribution of galaxy types and redshifts, the parameters of which are efficiently inferred from noisy photometric flux measurements. This approach can be seen as a generalization of template-fitting photometric redshift methods and relies on a library of spectral templates to relate the photometric fluxes of individual galaxies to their redshifts. We illustrate this technique on simulated galaxy survey data, and demonstrate that it delivers correct posterior distributions on the underlying type and redshift distributions, as well as on the individual types and redshifts of galaxies. We show that even with uninformative priors, large photometric errors and parameter degeneracies, the redshift and type distributions can be recovered robustly thanks to the hierarchical nature of the model, which is not possible with common photometric redshift estimation techniques. As a result, redshift uncertainties can be fully propagated in cosmological analyses for the first time, fulfilling an essential requirement for the current and future generations of surveys.

  5. Studying nearby disk galaxies with the CALIFA survey.

    NASA Astrophysics Data System (ADS)

    Marino, R. A.; Gil de Paz, A.; Sánchez, S. F.; Castillo-Morales, A.; CALIFA Team

    CALIFA, the Calar Alto Legacy Integral Field Area survey, will provide the largest and most comprehensive wide-field IFU survey of galaxies carried out to date, addressing several fundamental issues in galactic structure and evolution. We will observe a statistically well-defined sample of ˜ 600 galaxies in the local universe using 210 observing nights already awarded with the PMAS/PPAK integral field spectrophotometer, mounted on the Calar Alto 3.5m telescope. The definining science drivers for the project are: a) star formation and chemical history of galaxies, b) the physical state of the interstellar medium, c) stellar and gas kinematics in galaxies, and d) the influence of the AGNs on galaxy evolution. The CALIFA project comprises researchers from a large number of institutions worldwide: 8 institutions in Spain, 4 in Germany (CAHA funding countries) and 11 elsewhere, and includes a total of 56 researchers. CALIFA will provide a valuable bridge between large single-aperture surveys such as SDSS and more detailed studies of individual galaxies with PPAK (e.g. PINGS), SAURON, VIRUS-P, and other instruments.

  6. Galaxy and Group Baryonic Mass Functions for the RESOLVE Survey

    NASA Astrophysics Data System (ADS)

    Eckert, Kathleen D.; Kannappan, Sheila; Moffett, Amanda J.; Baker, Ashley; Stark, David; Berlind, Andreas A.; Storey-Fisher, Kate; Erickcek, Adrienne L.; Norris, Mark A.; Resolve Team

    2015-01-01

    We present a comparison of the galaxy and group baryonic mass functions for a subvolume of the RESOLVE (Resolved Spectroscopy Of a Local VolumE) survey. RESOLVE occupies A and B semester volumes totaling ~52,000 cubic Mpc, complete in baryonic mass to ~10^9.3 Msun and 10^9.0 Msun respectively, with galaxies and groups ranging in halo mass from 10^11-10^14 Msun. The A semester volume is surrounded by the larger ECO catalog, which lacks complete HI data but occupies ~561,000 cubic Mpc. We define the observed baryonic mass of a galaxy or group to be the sum of its stellar and cold atomic hydrogen components, with the latter inferred indirectly for much of ECO. For groups, we infer the total baryonic mass by summing the observed components of each constituent galaxy and add the likely hot halo gas based on prescriptions from observations and semi-analytic models. We perform subhalo/halo abundance matching between observed galaxies/groups and dark matter simulations, and we compare derived halo properties based on matching on luminosity vs. on observed baryonic mass (or on inferred total baryonic mass for groups). We also present a status update on the galaxy and group velocity functions for these surveys, which will allow for more direct comparison with dark matter simulations. This project was supported by NSF funding for the RESOLVE survey (AST-0955368).

  7. Methods for Bayesian power spectrum inference with galaxy surveys

    SciTech Connect

    Jasche, Jens; Wandelt, Benjamin D.

    2013-12-10

    We derive and implement a full Bayesian large scale structure inference method aiming at precision recovery of the cosmological power spectrum from galaxy redshift surveys. Our approach improves upon previous Bayesian methods by performing a joint inference of the three-dimensional density field, the cosmological power spectrum, luminosity dependent galaxy biases, and corresponding normalizations. We account for all joint and correlated uncertainties between all inferred quantities. Classes of galaxies with different biases are treated as separate subsamples. This method therefore also allows the combined analysis of more than one galaxy survey. In particular, it solves the problem of inferring the power spectrum from galaxy surveys with non-trivial survey geometries by exploring the joint posterior distribution with efficient implementations of multiple block Markov chain and Hybrid Monte Carlo methods. Our Markov sampler achieves high statistical efficiency in low signal-to-noise regimes by using a deterministic reversible jump algorithm. This approach reduces the correlation length of the sampler by several orders of magnitude, turning the otherwise numerically unfeasible problem of joint parameter exploration into a numerically manageable task. We test our method on an artificial mock galaxy survey, emulating characteristic features of the Sloan Digital Sky Survey data release 7, such as its survey geometry and luminosity-dependent biases. These tests demonstrate the numerical feasibility of our large scale Bayesian inference frame work when the parameter space has millions of dimensions. This method reveals and correctly treats the anti-correlation between bias amplitudes and power spectrum, which are not taken into account in current approaches to power spectrum estimation, a 20% effect across large ranges in k space. In addition, this method results in constrained realizations of density fields obtained without assuming the power spectrum or bias parameters

  8. The RSA survey of dwarf galaxies, 1: Optical photometry

    NASA Technical Reports Server (NTRS)

    Vader, J. Patricia; Chaboyer, Brian

    1994-01-01

    We present detailed surface photometry, based on broad B-band charge coupled device (CCD) images, of about 80 dwarf galaxies. Our sample represents approximately 10% of all dwarf galaxies identified in the vicinity of Revised Shapley-Ames (RSA) galaxies on high resolution blue photographic plates, referred to as the RSA survey of dwarf galaxies. We derive global properties and radial surface brightness profiles, and examine the morphologies. The radial surface brightness profiles of dwarf galaxies, whether early or late type, display the same varieties in shape and complexity as those of classical giant galaxies. Only a few are well described by a pure r(exp 1/4) law. Exponential profiles prevail. Features typical of giant disk galaxies, such as exponential profiles with a central depression, lenses, and even, in one case (IC 2041), a relatively prominent bulge are also found in dwarf galaxies. Our data suggest that the central region evolves from being bulge-like, with an r(exp 1/4) law profile, in bright galaxies to a lens-like structure in dwarf galaxies. We prove detailed surface photometry to be a helpful if not always sufficient tool in investigating the structure of dwarf galaxies. In many cases kinematic information is needed to complete the picture. We find the shapes of the surface brightness profiles to be loosely associated with morphological type. Our sample contains several new galaxies with properties intermediate between those of giant and dwarf ellipticals (but no M32-like objects). This shows that such intermediate galaxies exist so that at least a fraction of early-type dwarf ellipticals is structurally related to early-type giants instead of belonging to a totally unrelated, disjunct family. This supports an origin of early-type dwarf galaxies as originally more massive systems that acquired their current morphology as a result of substantial, presumable supernova-driven, mass loss. On the other hand, several early-type dwarfs in our sample are

  9. LUMINOUS STAR-FORMING GALAXIES IN THE GALAXY EVOLUTION EXPLORER-SLOAN DIGITAL SKY SURVEY DATABASE

    SciTech Connect

    Hutchings, J. B.; Bianchi, L.

    2010-02-15

    We have a Galaxy Evolution Explorer-Sloan Digital Sky Survey sample that isolates intermediate redshift QSOs. Some 1% of the spectroscopic sample consists of galaxies in starburst or post-starburst stages. We discuss the most luminous 10 of these, which have redshifts between 0.18 and 0.6. We present spectroscopic measures and derive star formation rates. Two of the six with Mg II coverage reveal outflows in this line. None shows any sign of active galactic nucleus activity. We discuss their star formation histories and their place in galaxy evolution.

  10. Scaling relations of early-type galaxies in the 6dF Galaxy Survey

    NASA Astrophysics Data System (ADS)

    Magoulas, C.; Colless, M.; Jones, H.; Mould, J.; Springob, C.

    2010-11-01

    Over 10,000 early-type galaxies from the 6dF Galaxy Survey (6dFGS) (Jones, D. H. et al. (2009), Jones et al. (2004)) have been used to determine the Fundamental Plane at optical and near-infrared wavelengths. We find that a maximum likelihood fit to an explicit three-dimensional Gaussian model for the distribution of galaxies in size, surface brightness and velocity dispersion can precisely account for selection effects, censoring and observational errors, leading to precise and unbiased parameters for the Fundamental Plane and its intrinsic scatter.

  11. The second byurakan survey galaxies. i. the optical database

    NASA Astrophysics Data System (ADS)

    Gyulzadyan, M.; McLean, B.; Adibekyan, V. Zh.; Allen, R. J.; Kunth, D.; Petrosian, A.; Stepanian, J. A.

    2011-03-01

    A database for the entire catalog of the Second Byurakan Survey (SBS) galaxies is presented. It contains new measurements of their optical parameters and additional information taken from the literature and other databases. The measurements were made using Ipg (near-infrared), Fpg (red), and Jpg (blue) band images from photographic sky survey plates obtained by the Palomar Schmidt telescope and extracted from the STScI Digital Sky Survey (DSS). The database provides accurate coordinates, morphological type, spectral and activity classes, apparent magnitudes and diameters, axial ratios and position angles, as well as number counts of neighboring objects in a circle of radius 50 kpc. The total number of individual SBS objects in the database is now 1676. The 188 Markarian galaxies that were re-discovered by SBS are not included in this database. We also include redshifts that are now available for 1576 SBS objects, as well as 2MASS infrared magnitudes for 1117 SBS galaxies.

  12. An HI Survey of Extremely Isolated Early-type Galaxies

    NASA Astrophysics Data System (ADS)

    Marcum, Pamela M.; Ashley, Trisha L.; Fanelli, Michael N.

    2016-01-01

    We present preliminary results from an HI survey of extremely isolated early-type galaxies (IEGs) conducted using the NRAO Robert C. Byrd Green Bank Telescope (GBT). The IEGs in our study are isolated to within 2.5 Mpc from other galaxies with luminosities brighter than MV=-16.5. The IEGs presented here are a subset of targets previously studied at shorter wavelengths. A large fraction of the IEGs shows evidence of recent or ongoing star formation, in contrast to their counterparts in higher density environments. The survey described here represents the first comprehensive assessment of neutral gas content within and around such systems. Preliminary findings from our HI survey indicate at least a quarter of the observed galaxies have detectable HI gas.

  13. Starbursts and Galaxy Evolution: results from COSMOS survey.

    NASA Astrophysics Data System (ADS)

    Muñoz-Tuñón, C.; Hinojosa Goñi, R.; Jairo Méndez Abreu, J.; Sánchez Alméida, J.

    2016-06-01

    The search for starbursts galaxies in COSMOS database by a tailored procedure that uses the photometry from SUBARU, results in 220 targets at z<0.5. The typical mass of the starburst is 10^8 and its distribution is similar to that of the quiescent galaxies in the survey at the same redshift range. From the detailed analysis of the galaxies images using the HST, the star forming clumps are characterized. The galaxies are of three different kinds, Snot, Snot and diffuse light and multiple knots. The mass of the knots are typically one order of magnitude below that of the host galaxy and the clumps in multiple knot galaxies are bigger the closer they are to the center. The sSFR however does not change with the particular position of the burst in their host galaxy, which suggests a similar process independently of their location. This result applies also to the galaxies at the largest z range (0.9). Our interpretation is that the star formation is happening at all possible locations on the galaxy discs, possibly from gas accreted from the halo or the IGM, with clumps which grow as they spiral and get to the centermost regions. Our previous work on nearby SF -tadpole galaxies of similar mass reported metallicity drops coinciding with the location of the burst what we have interpreted as SF driven by cold flows. Our results in COSMOS would be consistent with a similar interpretation and a scenario in which medium mass disks are growing by gas accretion that show up as scattered starbursts knots.

  14. Studying nearby disk galaxies with the CALIFA survey

    NASA Astrophysics Data System (ADS)

    Marino, R. A.; Gil de Paz, A.; Sánchez, S. F.; Castillo-Morales, A.

    2011-11-01

    CALIFA, the Calar Alto Legacy Integral Field Area survey, will provide the largest and most comprehensive wide-field IFU survey of galaxies carried out to date, combining the advantages of imaging and spectroscopy we will able to understand the origin for the observed diversity of galaxies, and the physical mechanisms -intrinsic and environmental- that are responsible for the differences as well as similarities between them. We will observe a statistically well-defined sample of ˜ 600 galaxies in the local universe (0.005 < z < 0.03) using 210 observing nights already awarded with the PMAS/PPAK integral field spectrophotometer, mounted on the Calar Alto 3.5 m telescope. PPAK offers a combination of extremely wide field-of-view (> 1 arcmin^2) with a high filling factor in one single pointing (65%), good spectral resolution, and wavelength sensitivity across the optical spectrum. The spectra will be covering the range 3700-7000 Å in two overlapping setups, one in the red (4300-7000 Å) at a spectral resolution of R ˜ 1000 and one in the blue (3700-5000 Å) at R ˜ 2000. The fully reduced and flux calibrated data of this legacy survey will be made available to the public. Some of definining science drivers for the CALIFA project are the star formation and the chemical history of galaxies; the study of the physical state of the interstellar medium; improve our knowledge on the stellar and gas kinematics in galaxies, and understand the influence of the AGNs on galaxy evolution. The CALIFA project comprises researchers from a large number of institutions worldwide: 8 institutions in Spain, 4 in Germany (CAHA funding countries) and 11 elsewhere, and includes a total of 56 researchers. CALIFA will provide a valuable bridge between large single-aperture surveys such as SDSS and more detailed studies of individual galaxies with PPAK (e.g. PINGS), SAURON, VIRUS-P, and other instruments.

  15. Can a galaxy redshift survey measure dark energy clustering?

    SciTech Connect

    Takada, Masahiro

    2006-08-15

    A wide-field galaxy redshift survey allows one to probe galaxy clustering at largest spatial scales, which carries invaluable information on horizon-scale physics complementarily to the cosmic microwave background (CMB). Assuming the planned survey consisting of z{approx}1 and z{approx}3 surveys with areas of 2000 and 300 deg.{sup 2}, respectively, we study the prospects for probing dark energy clustering from the measured galaxy power spectrum, assuming the dynamical properties of dark energy are specified in terms of the equation of state and the effective sound speed c{sub e} in the context of an adiabatic cold dark dominated matter model. The dark energy clustering adds a power to the galaxy power spectrum amplitude at spatial scales greater than the sound horizon, and the enhancement is sensitive to redshift evolution of the net dark energy density, i.e. the equation of state. We find that the galaxy survey, when combined with CMB expected from the Planck satellite mission, can distinguish dark energy clustering from a smooth dark energy model such as the quintessence model (c{sub e}=1), when c{sub e} < or approx. 0.04 (0.02) in the case of the constant equation of state w{sub 0}=-0.9 (-0.95). An ultimate full-sky survey of z{approx}1 galaxies allows the detection when c{sub e}(less-or-similar sign)0.08 (0.04) for w{sub 0}=0.9 (-0.95). These forecasts show a compatible power with an all-sky CMB and galaxy cross correlation that probes the integrated Sachs-Wolfe effect. We also investigate a degeneracy between the dark energy clustering and the nonrelativistic neutrinos implied from the neutrino oscillation experiments, because the two effects both induce a scale-dependent modification in the galaxy power spectrum shape at largest spatial scales accessible from the galaxy survey. It is shown that a wider redshift coverage can efficiently separate the two effects by utilizing the different redshift dependences, where dark energy clustering is apparent only at

  16. The SAMI Galaxy Survey: Spatially resolving the environmental quenching of star formation in GAMA galaxies

    NASA Astrophysics Data System (ADS)

    Schaefer, A. L.; Croom, S. M.; Allen, J. T.; Brough, S.; Medling, A. M.; Ho, I.-T.; Scott, N.; Richards, S. N.; Pracy, M. B.; Gunawardhana, M. L. P.; Norberg, P.; Alpaslan, M.; Bauer, A. E.; Bekki, K.; Bland-Hawthorn, J.; Bloom, J. V.; Bryant, J. J.; Couch, W. J.; Driver, S. P.; Fogarty, L. M. R.; Foster, C.; Goldstein, G.; Green, A. W.; Hopkins, A. M.; Konstantopoulos, I. S.; Lawrence, J. S.; López-Sánchez, A. R.; Lorente, N. P. F.; Owers, M. S.; Sharp, R.; Sweet, S. M.; Taylor, E. N.; van de Sande, J.; Walcher, C. J.; Wong, O. I.

    2016-09-01

    We use data from the Sydney-AAO Multi-Object Integral Field Spectrograph (SAMI) Galaxy Survey and the Galaxy And Mass Assembly (GAMA) survey to investigate the spatially-resolved signatures of the environmental quenching of star formation in galaxies. Using dust-corrected measurements of the distribution of Hα emission we measure the radial profiles of star formation in a sample of 201 star-forming galaxies covering three orders of magnitude in stellar mass ({M}_{*}; 108.1-1010.95 M⊙) and in 5th nearest neighbour local environment density (Σ5; 10-1.3- 102.1 Mpc-2). We show that star formation rate gradients in galaxies are steeper in dense (log10(Σ5/Mpc2) > 0.5) environments by 0.58 ± 0.29 dex re-1 in galaxies with stellar masses in the range 1010 < M★/M⊙ < 1011 and that this steepening is accompanied by a reduction in the integrated star formation rate. However, for any given stellar mass or environment density the star-formation morphology of galaxies shows large scatter. We also measure the degree to which the star formation is centrally concentrated using the unitless scale-radius ratio (r50, Hα/r50, cont), which compares the extent of ongoing star formation to previous star formation. With this metric we find that the fraction of galaxies with centrally concentrated star formation increases with environment density, from ˜5 ± 4% in low-density environments (log10(Σ5/Mpc2) < 0.0) to 30 ± 15% in the highest density environments (log10(Σ5/Mpc2) > 1.0). These lines of evidence strongly suggest that with increasing local environment density the star formation in galaxies is suppressed, and that this starts in their outskirts such that quenching occurs in an outside-in fashion in dense environments and is not instantaneous.

  17. The Void Galaxy Survey: Galaxy Evolution and Gas Accretion in Voids

    NASA Astrophysics Data System (ADS)

    Kreckel, Kathryn; van Gorkom, Jacqueline H.; Beygu, Burcu; van de Weygaert, Rien; van der Hulst, J. M.; Aragon-Calvo, Miguel A.; Peletier, Reynier F.

    2016-10-01

    Voids represent a unique environment for the study of galaxy evolution, as the lower density environment is expected to result in shorter merger histories and slower evolution of galaxies. This provides an ideal opportunity to test theories of galaxy formation and evolution. Imaging of the neutral hydrogen, central in both driving and regulating star formation, directly traces the gas reservoir and can reveal interactions and signs of cold gas accretion. For a new Void Galaxy Survey (VGS), we have carefully selected a sample of 59 galaxies that reside in the deepest underdensities of geometrically identified voids within the SDSS at distances of ~100 Mpc, and pursued deep UV, optical, Hα, IR, and HI imaging to study in detail the morphology and kinematics of both the stellar and gaseous components. This sample allows us to not only examine the global statistical properties of void galaxies, but also to explore the details of the dynamical properties. We present an overview of the VGS, and highlight key results on the HI content and individually interesting systems. In general, we find that the void galaxies are gas rich, low luminosity, blue disk galaxies, with optical and HI properties that are not unusual for their luminosity and morphology. We see evidence of both ongoing assembly, through the gas dynamics between interacting systems, and significant gas accretion, seen in extended gas disks and kinematic misalignments. The VGS establishes a local reference sample to be used in future HI surveys (CHILES, DINGO, LADUMA) that will directly observe the HI evolution of void galaxies over cosmic time.

  18. The Dragonfly nearby Galaxies Survey. I. Substantial Variation in the Diffuse Stellar Halos around Spiral Galaxies

    NASA Astrophysics Data System (ADS)

    Merritt, Allison; van Dokkum, Pieter; Abraham, Roberto; Zhang, Jielai

    2016-10-01

    Galaxies are thought to grow through accretion; as less massive galaxies are disrupted and merge over time, their debris results in diffuse, clumpy stellar halos enveloping the central galaxy. Here we present a study of the variation in the stellar halos of galaxies, using data from the Dragonfly Nearby Galaxies Survey (DNGS). The survey consists of wide field, deep ({μ }g\\gt 31 mag arcsec‑2) optical imaging of nearby galaxies using the Dragonfly Telephoto Array. Our sample includes eight spiral galaxies with stellar masses similar to that of the Milky Way, inclinations of 16-19 degrees and distances between 7-18 Mpc. We construct stellar mass surface density profiles from the observed g-band surface brightness in combination with the g ‑ r color as a function of radius, and compute the halo fractions from the excess stellar mass (relative to a disk+bulge fit) beyond 5 half-mass radii. We find a mean halo fraction of 0.009 ± 0.005 and a large rms scatter of {1.01}-0.26+0.9 dex. The peak-to-peak scatter of the halo fraction is a factor of \\gt 100—while some galaxies feature strongly structured halos resembling that of M31, three of the eight have halos that are completely undetected in our data. We conclude that spiral galaxies as a class exhibit a rich variety in stellar halo properties, implying that their assembly histories have been highly non-uniform. We find no convincing evidence for an environmental or stellar mass dependence of the halo fraction in the sample.

  19. GIANT GALAXIES, DWARFS, AND DEBRIS SURVEY. I. DWARF GALAXIES AND TIDAL FEATURES AROUND NGC 7331

    SciTech Connect

    Ludwig, Johannes; Pasquali, Anna; Grebel, Eva K.; Gallagher, John S. III

    2012-12-01

    The Giant GAlaxies, Dwarfs, and Debris Survey (GGADDS) concentrates on the nearby universe to study how galaxies have interacted in groups of different morphology, density, and richness. In these groups, we select the dominant spiral galaxy and search its surroundings for dwarf galaxies and tidal interactions. This paper presents the first results from deep wide-field imaging of NGC 7331, where we detect only four low-luminosity candidate dwarf companions and a stellar stream that may be evidence of a past tidal interaction. The dwarf galaxy candidates have surface brightnesses of {mu}{sub r} Almost-Equal-To 23-25 mag arcsec{sup -2} with (g - r){sub 0} colors of 0.57-0.75 mag in the Sloan Digital Sky Survey filter system, consistent with their being dwarf spheroidal (dSph) galaxies. A faint stellar stream structure on the western edge of NGC 7331 has {mu}{sub g} Almost-Equal-To 27 mag arcsec{sup -2} and a relatively blue color of (g - r){sub 0} = 0.15 mag. If it is tidal debris, then this stream could have formed from a rare type of interaction between NGC 7331 and a dwarf irregular or transition-type dwarf galaxy. We compare the structure and local environments of NGC 7331 to those of other nearby giant spirals in small galaxy groups. NGC 7331 has a much lower ({approx}2%) stellar mass in the form of early-type satellites than found for M31 and lacks the presence of nearby companions like luminous dwarf elliptical galaxies or the Magellanic Clouds. However, our detection of a few dSph candidates suggests that it is not deficient in low-luminosity satellites.

  20. Surveying for Dwarf Galaxies Within Void FN8

    NASA Astrophysics Data System (ADS)

    McNeil, Stephen R.

    2016-06-01

    The dwarf galaxy population in low density volumes, or voids, is a test of galaxy formation models and how they treat dark matter; some models say dwarf galaxies cannot be in void centers while others say they can. Since it appears many dwarf galaxies are H-alpha emitters, a well-designed deep survey through a nearby void center will either find nothing, and thus constrain the population there to be at some percentage below the mean, or it will find H-alpha emitters and significantly challenge several otherwise successful theories. Either result is a significant step in better understanding galaxy formation and large-scale structure. In 2013, a redshifted H-alpha imaging survey was begun for dwarf galaxies with ‑14.0 ≤ Mr ≤ ‑12.0 in the heart and back of the void FN8. Our first results have been surprising, furnishing significantly more candidate objects than anticipated. Through the Gemini Fast Turnaround Program, seven spectrum have been obtained, with one spectrum being a strong candidate for habitation within the center of the void.

  1. AGN identification and host galaxies properties in the MOSDEF survey

    NASA Astrophysics Data System (ADS)

    Azadi, Mojegan; Coil, Alison L.; MOSDEF Team

    2016-06-01

    We present new results on the identification and host galaxy properties of X-ray, IR and optically-selected AGN at 1.4 < z < 3.8, using spectroscopic data from the on-going MOSDEF survey, which is obtaining rest-frame optical spectra of ~1,500 galaxies and AGN using the new Keck/MOSFIRE instrument. We find clear selection effects when identifying AGN at different wavelengths, in that optically-selected AGN are more likely to be found in galaxies with low SFR, while IR AGN are typically found in galaxies with higher SFR. There is also a bias against finding AGN at any wavelength in low mass galaxies. We find that optical AGN selection identifies less powerful AGN that may be obscured at other wavelengths. Combining the AGN we identify at different wavelengths, we find that AGN host galaxies have similar stellar age and dust content as inactive galaxies of the same stellar mass. Finally, we do not find a significant correlation between either SFR or stellar mass and L[OIII], which argues against the presence of strong AGN feedback.

  2. AGN Identification and Host Galaxy Properties in the MOSDEF Survey

    NASA Astrophysics Data System (ADS)

    Coil, Alison

    2016-08-01

    I will present new results on the identification and host galaxy properties of X-ray, IR, and optically-selected AGN at 1.4 < z < 3.8, using spectroscopic data from the on-going MOSDEF survey. MOSDEF is obtaining rest-frame optical spectra of ~1300 galaxies and AGN using the newly commissioned MOSFIRE instrument on Keck. We find clear selection biases when identifying AGN at different wavelengths, in that AGN at any wavelength are typically found in more massive galaxies, while optically-selected AGN are also more likely to be found in galaxies with low SFR, while IR AGN are typically found in galaxies with higher SFR. We also find that optical and X-ray AGN selection identifies AGN with a wider range of accretion rates than IR AGN selection. By combining AGN samples selected at different wavelengths, we find that AGN host galaxies have similar stellar age and dust content as inactive galaxies of the same stellar mass.

  3. LENSING NOISE IN MILLIMETER-WAVE GALAXY CLUSTER SURVEYS

    SciTech Connect

    Hezaveh, Yashar; Vanderlinde, Keith; Holder, Gilbert; De Haan, Tijmen

    2013-08-01

    We study the effects of gravitational lensing by galaxy clusters of the background of dusty star-forming galaxies (DSFGs) and the cosmic microwave background (CMB), and examine the implications for Sunyaev-Zel'dovich-based (SZ) galaxy cluster surveys. At the locations of galaxy clusters, gravitational lensing modifies the probability distribution of the background flux of the DSFGs as well as the CMB. We find that, in the case of a single-frequency 150 GHz survey, lensing of DSFGs leads both to a slight increase ({approx}10%) in detected cluster number counts (due to a {approx}50% increase in the variance of the DSFG background, and hence an increased Eddington bias) and a rare (occurring in {approx}2% of clusters) 'filling-in' of SZ cluster signals by bright strongly lensed background sources. Lensing of the CMB leads to a {approx}55% reduction in CMB power at the location of massive galaxy clusters in a spatially matched single-frequency filter, leading to a net decrease in detected cluster number counts. We find that the increase in DSFG power and decrease in CMB power due to lensing at cluster locations largely cancel, such that the net effect on cluster number counts for current SZ surveys is subdominant to Poisson errors.

  4. Galaxy Zoo: morphologies derived from visual inspection of galaxies from the Sloan Digital Sky Survey

    NASA Astrophysics Data System (ADS)

    Lintott, Chris J.; Schawinski, Kevin; Slosar, Anže; Land, Kate; Bamford, Steven; Thomas, Daniel; Raddick, M. Jordan; Nichol, Robert C.; Szalay, Alex; Andreescu, Dan; Murray, Phil; Vandenberg, Jan

    2008-09-01

    In order to understand the formation and subsequent evolution of galaxies one must first distinguish between the two main morphological classes of massive systems: spirals and early-type systems. This paper introduces a project, Galaxy Zoo, which provides visual morphological classifications for nearly one million galaxies, extracted from the Sloan Digital Sky Survey (SDSS). This achievement was made possible by inviting the general public to visually inspect and classify these galaxies via the internet. The project has obtained more than 4 × 107 individual classifications made by ~105 participants. We discuss the motivation and strategy for this project, and detail how the classifications were performed and processed. We find that Galaxy Zoo results are consistent with those for subsets of SDSS galaxies classified by professional astronomers, thus demonstrating that our data provide a robust morphological catalogue. Obtaining morphologies by direct visual inspection avoids introducing biases associated with proxies for morphology such as colour, concentration or structural parameters. In addition, this catalogue can be used to directly compare SDSS morphologies with older data sets. The colour-magnitude diagrams for each morphological class are shown, and we illustrate how these distributions differ from those inferred using colour alone as a proxy for morphology. This publication has been made possible by the participation of more than 100000 volunteers in the Galaxy Zoo project. Their contributions are individually acknowledged at http://www.galaxyzoo.org/Volunteers.aspx E-mail: cjl@astro.ox.ac.uk (CJL); kevins@astro.ox.ac.uk (KS)

  5. Completing the survey of the most massive southern galaxy clusters

    NASA Astrophysics Data System (ADS)

    Boehringer, Hans

    2014-09-01

    With the recently completed REFLEX II galaxy cluster survey we obtained a new sample of the most X-ray luminous and most massive galaxy clusters comprising a total of 45 galaxy clusters (Lx>=6e44 erg/s) at z>=0.3 in the southern sky. The majority of these prominent clusters have been detected in various surveys and have been well studied in X-rays before, except for 8 clusters in our new sample. These clusters are the most interesting objects of this kind since they are prominent gravitational lensing objects, easily detected through the Sunyaev-Zeldovich effect, and important cosmological probes. To complete this sample of massive clusters, we propose Chandra observations with a total of 220 ks exposure to well characterize their global parameters and explore their morphology.

  6. The DEEP2 Galaxy Redshift Survey: The Voronoi-Delaunay Method Catalog of Galaxy Groups

    SciTech Connect

    Gerke, Brian F.; Newman, Jeffrey A.; Davis, Marc; Marinoni, Christian; Yan, Renbin; Coil, Alison L.; Conroy, Charlie; Cooper, Michael C.; Faber, S.M.; Finkbeiner, Douglas P.; Guhathakurta, Puragra; Kaiser, Nick; Koo, David C.; Phillips, Andrew C.; Weiner, Benjamin J.; /Maryland U.

    2012-02-14

    We use the first 25% of the DEEP2 Galaxy Redshift Survey spectroscopic data to identify groups and clusters of galaxies in redshift space. The data set contains 8370 galaxies with confirmed redshifts in the range 0.7 {<=} z {<=} 1.4, over one square degree on the sky. Groups are identified using an algorithm (the Voronoi-Delaunay Method) that has been shown to accurately reproduce the statistics of groups in simulated DEEP2-like samples. We optimize this algorithm for the DEEP2 survey by applying it to realistic mock galaxy catalogs and assessing the results using a stringent set of criteria for measuring group-finding success, which we develop and describe in detail here. We find in particular that the group-finder can successfully identify {approx}78% of real groups and that {approx}79% of the galaxies that are true members of groups can be identified as such. Conversely, we estimate that {approx}55% of the groups we find can be definitively identified with real groups and that {approx}46% of the galaxies we place into groups are interloper field galaxies. Most importantly, we find that it is possible to measure the distribution of groups in redshift and velocity dispersion, n({sigma}, z), to an accuracy limited by cosmic variance, for dispersions greater than 350 km s{sup -1}. We anticipate that such measurements will allow strong constraints to be placed on the equation of state of the dark energy in the future. Finally, we present the first DEEP2 group catalog, which assigns 32% of the galaxies to 899 distinct groups with two or more members, 153 of which have velocity dispersions above 350 km s{sup -1}. We provide locations, redshifts and properties for this high-dispersion subsample. This catalog represents the largest sample to date of spectroscopically detected groups at z {approx} 1.

  7. Cluster galaxy evolution with the Las Campanas Distant Cluster Survey

    NASA Astrophysics Data System (ADS)

    Nelson, Amy Elizabeth

    Understanding the formation and evolution of galaxies is a principal goal of modern cosmology. In this thesis, we place constraints on galaxy evolution models using the largest sample of high redshift clusters to date. Our sample consists of 63 clusters at 0.3 ≲ z ≲ 0.9 drawn from the Las Campanas Distant Cluster Survey (LCDCS). This survey differs from traditional optical surveys in that we detect clusters as regions of excess surface brightness relative to the background sky rather than selecting overdensities of resolved galaxies. Therefore, not only does this sample result in a significant increase in the number of known clusters at these redshifts, but because our cluster identification criteria is independent of those utilized in previous surveys, this catalog provides an independent, well-defined sample with which to compare the results of more traditional surveys. In this work, we take a two-pronged approach to studying galaxy evolution. First, we examine the luminosity and color evolution of the bright cluster galaxies as a class. Specifically, we measure the evolution of: (1) M*I , the characteristic luminosity of cluster galaxies, (2) the location of the red envelope in V--I and I--K', and (3) the fraction of blue galaxies (i.e. the Butcher-Oemler effect; Butcher & Oemler 1984). Our data suggest that luminous early type galaxies (or the progenitors of current day early type galaxies) form the bulk of their stellar populations at high redshifts ( ≲ 5) and that many of these galaxies, if not all, experience a short term episode of star formation at lower redshifts (1.5 < z < 2). Second, we narrow the focus and study a single type of cluster galaxy, the brightest cluster galaxy (BCG). We constrain the amount of luminosity and color evolution of BCGs, particularly in the context of recent claims in the literature of significant mass accretion since z ˜ 1 (Aragon-Salamanca 1998; Burke, Collins, & Mann 2000). Consistent with previous results (Burke

  8. GALAXY CLUSTERING TOPOLOGY IN THE SLOAN DIGITAL SKY SURVEY MAIN GALAXY SAMPLE: A TEST FOR GALAXY FORMATION MODELS

    SciTech Connect

    Choi, Yun-Young; Kim, Juhan; Kim, Sungsoo S.; Park, Changbom; Gott, J. Richard; Weinberg, David H.; Vogeley, Michael S.

    2010-09-15

    We measure the topology of the main galaxy distribution using the Seventh Data Release of the Sloan Digital Sky Survey, examining the dependence of galaxy clustering topology on galaxy properties. The observational results are used to test galaxy formation models. A volume-limited sample defined by M{sub r} < -20.19 enables us to measure the genus curve with an amplitude of G = 378 at 6 h {sup -1} Mpc smoothing scale, with 4.8% uncertainty including all systematics and cosmic variance. The clustering topology over the smoothing length interval from 6 to 10 h {sup -1} Mpc reveals a mild scale dependence for the shift ({Delta}{nu}) and void abundance (A{sub V}) parameters of the genus curve. We find substantial bias in the topology of galaxy clustering with respect to the predicted topology of the matter distribution, which varies with luminosity, morphology, color, and the smoothing scale of the density field. The distribution of relatively brighter galaxies shows a greater prevalence of isolated clusters and more percolated voids. Even though early (late)-type galaxies show topology similar to that of red (blue) galaxies, the morphology dependence of topology is not identical to the color dependence. In particular, the void abundance parameter A{sub V} depends on morphology more strongly than on color. We test five galaxy assignment schemes applied to cosmological N-body simulations of a {Lambda}CDM universe to generate mock galaxies: the halo-galaxy one-to-one correspondence model, the halo occupation distribution model, and three implementations of semi-analytic models (SAMs). None of the models reproduces all aspects of the observed clustering topology; the deviations vary from one model to another but include statistically significant discrepancies in the abundance of isolated voids or isolated clusters and the amplitude and overall shift of the genus curve. SAM predictions of the topology color dependence are usually correct in sign but incorrect in magnitude

  9. The SAMI Galaxy Survey: One Year, 50000 Spectra

    NASA Astrophysics Data System (ADS)

    Konstantopoulos, Iraklis; Croom, S.; The SAMI Galaxy Survey Team

    2014-01-01

    Less than a year into its operations on the Anglo-Australian Telescope, the SAMI Galaxy Survey has collected spatially resolved (IFU) spectroscopy of 440 galaxies. This breaks all previous records owing to the novel 13-fold multiplexing of the newly-designed, lightly-fused 'hexabundles' of 61 optical fibre cores that can be deployed over a degree-wide field. (Illustrations can be found in the partner poster presentation by Gerald Cecil and at http://sami-survey.org.) On our way toward the completion of a ~3000-galaxy-strong sample, that is, of order 4x105 full-optical spectra, we are working on the key scientific objectives of: (i) Mapping the mechanisms that advance and suppress the star formation process and induce morphological transformation in a variety of environments; (ii) Surveying the frequency of gas flows into and out of galaxies of all masses, and deducing the effect on gas phase metallicity and baryonic budgets; (iii) Recording the distribution of angular momentum across the local Universe, thereby advancing our understanding of how mass is built up over time. Our simulations team is working in parallel with the observers to produce mock SAMI data-cubes and interpret our results in a cosmological context. Furthermore, having selected most of our sample from the all-wavelength GAMA survey affords us access to invaluable ancillary information. The SAMI Galaxy Survey, which adds resolved stellar and gas phase kinematics, star formation rates, ionisation diagnostics, stellar ages, metallicities, and much more will provide a unique and long lasting legacy for the astronomical community.

  10. The bispectrum of galaxies from high-redshift galaxy surveys: Primordial non-Gaussianity and non-linear galaxy bias

    SciTech Connect

    Sefusatti, Emiliano; Komatsu, Eiichiro; /Texas U., Astron. Dept.

    2007-05-01

    The greatest challenge in the interpretation of galaxy clustering data from any surveys is galaxy bias. Using a simple Fisher matrix analysis, we show that the bispectrum provides an excellent determination of linear and non-linear bias parameters of intermediate and high-z galaxies, when all measurable triangle configurations down to mildly non-linear scales, where perturbation theory is still valid, are included. The bispectrum is also a powerful probe of primordial non-Gaussianity. The planned galaxy surveys at z {approx}> 2 should yield constraints on non-Gaussian parameters, f{sub NL}{sup loc.} and f{sub NL}{sup eq.}, that are comparable to, or even better than, those from CMB experiments. We study how these constraints improve with volume, redshift range, as well as the number density of galaxies. Finally we show that a halo occupation distribution may be used to improve these constraints further by lifting degeneracies between gravity, bias, and primordial non-Gaussianity.

  11. The ALHAMBRA Survey: Evolution of Galaxy Spectral Segregation

    NASA Astrophysics Data System (ADS)

    Hurtado-Gil, Ll.; Arnalte-Mur, P.; Martínez, V. J.; Fernández-Soto, A.; Stefanon, M.; Ascaso, B.; López-Sanjuán, C.; Márquez, I.; Pović, M.; Viironen, K.; Aguerri, J. A. L.; Alfaro, E.; Aparicio-Villegas, T.; Benítez, N.; Broadhurst, T.; Cabrera-Caño, J.; Castander, F. J.; Cepa, J.; Cerviño, M.; Cristóbal-Hornillos, D.; González Delgado, R. M.; Husillos, C.; Infante, L.; Masegosa, J.; Moles, M.; Molino, A.; del Olmo, A.; Paredes, S.; Perea, J.; Prada, F.; Quintana, J. M.

    2016-02-01

    We study the clustering of galaxies as a function of spectral type and redshift in the range 0.35 < z < 1.1 using data from the Advanced Large Homogeneous Area Medium Band Redshift Astronomical (ALHAMBRA) survey. The data cover 2.381 deg2 in 7 fields, after applying a detailed angular selection mask, with accurate photometric redshifts {{[}}{σ }z\\lt 0.014(1+z){{]}} down to IAB < 24. From this catalog we draw five fixed number density redshift-limited bins. We estimate the clustering evolution for two different spectral populations selected using the ALHAMBRA-based photometric templates: quiescent and star-forming galaxies. For each sample we measure the real-space clustering using the projected correlation function. Our calculations are performed over the range [0.03, 10.0] h-1 Mpc, allowing us to find a steeper trend for {r}p≲ 0.2 {h}-1 Mpc, which is especially clear for star-forming galaxies. Our analysis also shows a clear early differentiation in the clustering properties of both populations: star-forming galaxies show weaker clustering with evolution in the correlation length over the analyzed redshift range, while quiescent galaxies show stronger clustering already at high redshifts and no appreciable evolution. We also perform the bias calculation where similar segregation is found, but now it is among the quiescent galaxies where a growing evolution with redshift is clearer (abrigatted). These findings clearly corroborate the well-known color-density relation, confirming that quiescent galaxies are mainly located in dark matter halos that are more massive than those typically populated by star-forming galaxies.

  12. The Galaxy Evolution Explorer (GALEX): an All Sky Ultraviolet Survey

    NASA Astrophysics Data System (ADS)

    Bianchi, Luciana; GALEX Team

    We are preparing a mission to perform imaging and spectroscopic surveys of the sky in the Ultraviolet. GALEX (The GALaxy Evolution EXplorer) will fill in the crucial missing piece of the spectrum so that our knowledge of the sky from 100 micron to 10 A is complete. The Palomar Sky Survey has served as the fundamental resource for research in optical astronomy for over thirty years, and the IRAS, EUVE, and Rosat satellites provided similar databases for the infrared, extreme ultraviolet, and X-ray regimes. GALEX will provide a catalog with an order of magnitude more sources than any of these experiments, and will produce an unprecedented statistically powerful database of UV images and spectra of nearby and distant galaxies, linked to a multiwavelength archive. GALEX is approved as a NASA Small Explorer (SMEX) mission, to fly in 2001. GALEX will perform a series of spectroscopic and imaging surveys in the space ultraviolet band (1300-3000A ), that will map the history and probe the causes of star formation over the 0galaxy disks were formed. GALEX will provide a direct measurement of each the redshift (using metal lines and the Lyman break), extinction (using the UV spectral slope), and star formation rate (UV luminosity) in 100,000 galaxies, with efficient slitless grism spectroscopy. It will determine whether rapid evolution has occured in the star formation rate, or in the extinction or initial mass function. The GALEX database will furnish a direct link between rest frame UV properties of galaxies seen locally to those that dominate the faint blue galaxy population. As such, it will provide a framework for the interpretation of the deepest HST images and those that may be obtained by the NGST.

  13. SHARDS: AN OPTICAL SPECTRO-PHOTOMETRIC SURVEY OF DISTANT GALAXIES

    SciTech Connect

    Perez-Gonzalez, Pablo G.; Cava, Antonio; Barro, Guillermo; Villar, Victor; Cardiel, Nicolas; Espino, Nestor; Gallego, Jesus; Ferreras, Ignacio; Rodriguez-Espinosa, Jose Miguel; Balcells, Marc; Cepa, Jordi; Alonso-Herrero, Almudena; Cenarro, Javier; Charlot, Stephane; Cimatti, Andrea; Conselice, Christopher J.; Daddi, Emmanuele; Elbaz, David; Gobat, R. [Laboratoire AIM-Paris-Saclay, CEA and others

    2013-01-01

    We present the Survey for High-z Absorption Red and Dead Sources (SHARDS), an ESO/GTC Large Program carried out using the OSIRIS instrument on the 10.4 m Gran Telescopio Canarias (GTC). SHARDS is an ultra-deep optical spectro-photometric survey of the GOODS-N field covering 130 arcmin{sup 2} at wavelengths between 500 and 950 nm with 24 contiguous medium-band filters (providing a spectral resolution R {approx} 50). The data reach an AB magnitude of 26.5 (at least at a 3{sigma} level) with sub-arcsec seeing in all bands. SHARDS' main goal is to obtain accurate physical properties of intermediate- and high-z galaxies using well-sampled optical spectral energy distributions (SEDs) with sufficient spectral resolution to measure absorption and emission features, whose analysis will provide reliable stellar population and active galactic nucleus (AGN) parameters. Among the different populations of high-z galaxies, SHARDS' principal targets are massive quiescent galaxies at z > 1, whose existence is one of the major challenges facing current hierarchical models of galaxy formation. In this paper, we outline the observational strategy and include a detailed discussion of the special reduction and calibration procedures which should be applied to the GTC/OSIRIS data. An assessment of the SHARDS data quality is also performed. We present science demonstration results on the detection and study of emission-line galaxies (star-forming objects and AGNs) at z = 0-5. We also analyze the SEDs for a sample of 27 quiescent massive galaxies with spectroscopic redshifts in the range 1.0 < z {approx}< 1.4. We discuss the improvements introduced by the SHARDS data set in the analysis of their star formation history and stellar properties. We discuss the systematics arising from the use of different stellar population libraries, typical in this kind of study. Averaging the results from the different libraries, we find that the UV-to-MIR SEDs of the massive quiescent galaxies at z = 1

  14. The Byurakan-IRAS Galaxy (BIG) Sample: The Redshift Survey

    NASA Astrophysics Data System (ADS)

    Mickaelian, Areg M.; Balayan, Smbat K.; Hakopian, Susanna A.

    The Byurakan-IRAS Galaxy (BIG) sample (1513 galaxies) is based on optical identifications of IRAS PSC sources at DEC > +61 and b > 15 (FBS area). A redshift survey for brighter objects (B < 18) is being carried out with 3 telescopes: Byurakan Observatory 2.6m, Special Observatory (Russia) 6m, and Observatoire de Haute-Provence 1.93m. 200 objects have been observed, and redshifts in the range 0.009-0.173 have been measured. For this subsample, 15% of objects are AGNs, and 5% are LIGs and ULIGs. Interesting cases of AGN containing interacting pairs are being studied by means of the 2D spectroscopy.

  15. The XXL survey: first results on clusters of galaxy

    NASA Astrophysics Data System (ADS)

    Pacaud, Florian

    2016-07-01

    With a total geometric area of 50deg2, XXL is the largest contiguous survey undertaken by the XMM-Newton satellite. The final survey catalogues are expected to contain ~25000 AGNs down to a flux limit of 3e-15 erg/s/cm2 and ~500 groups and clusters of galaxies up to a redshift of z~1.5. The first results of the survey focus on a sub-sample of the 100 brightest galaxy clusters and have recently been released to the public. In this contribution, I will first describe the sample and the modeling of its selection function. Then, I will discuss some of the most significant early scientific results based on the catalogue, namely the measured scaling relations, the baryon budget of XXL groups, the detection of superstructures and the cosmological implications of the sample.

  16. Luminous red galaxies in the Sloan digital sky survey

    NASA Astrophysics Data System (ADS)

    Loh, Yeong-Shang

    2004-04-01

    We determine the luminosity function and evolution of 22,562 Luminous Red Galaxies (LRG) with 0.08 < z < 0.44 from the Sloan Digital Sky Survey (SDSS). The universal field galaxy luminosity function with a steep exponential bright end cut-off expected from a Schechter form is confirmed to z ˜ 0.4. We do not discern any evolution in the comoving number density of these luminous early-type galaxies, once biases due to photometric errors are taken into account. Using 2099 deg2 of SDSS imaging data, we search for bright early-type galaxies within 1 h-1 Mpc of LRG with 0.12 < z < 0.38 to study the bright end of the luminosity distribution at this scale. The brightest galaxies (nearly always an LRG) in LRG fields are too bright if other members in the same field are drawn from an exponentially decaying luminosity function. The luminosity gap between the brightest and the second brightest galaxy is large (˜0.8 mag). When the LRG fields were split into group-like and cluster- like environments, the former gives a larger gap. The gap shows little evolution with redshifts, putting stringent constraints on the scenario of the growth of Brightest Cluster (or Group) Galaxies by recent cannibalism of cluster members. We calibrate the observed color-magnitude-redshift relation for early-type galaxies. We use LRGs as spectroscopic references and measure the color of imaging galaxies that clustered around each LRG. We bin these galaxies in redshift and perform an optimal background subtraction to recover the color-magnitude relation. The observed scatter around this color-magnitude relation is also measured. We study the environments of LRG by counting the number of early-type galaxies brighter than M* within 1 h-1 Mpc of the LRG. LRGs are binned in redshift and treated as a single population to infer the evolution trend of their environments. Both the rich optical clusters and moderately X-ray bright clusters host at least one LRG. However, LRG are most common in group

  17. Shapley Supercluster Survey: Galaxy evolution from filaments to cluster cores

    NASA Astrophysics Data System (ADS)

    Merluzzi, P.; Busarello, G.; Haines, C. P.; Mercurio, A.; Okabe, N.; Pimbblet, K. J.; Dopita, M. A.; Grado, A.; Limatola, L.; Bourdin, H.; Mazzotta, P.; Capaccioli, M.; Napolitano, N. R.; Schipani, P.

    2015-01-01

    We present an overview of a multiwavelength survey of the Shapley Supercluster (SSC; z ˜ 0.05) covering a contiguous area of 260 h^{-2}_{70} Mpc2 including the supercluster core. The project main aim is to quantify the influence of cluster-scale mass assembly on galaxy evolution in one of the most massive structures in the local Universe. The Shapley Supercluster Survey (ShaSS) includes nine Abell clusters (A3552, A3554, A3556, A3558, A3559, A3560, A3562, AS0724, AS0726) and two poor clusters (SC1327-312, SC1329-313) showing evidence of cluster-cluster interactions. Optical (ugri) and near-infrared (K) imaging acquired with VLT Survey Telescope and Visible and Infrared Survey Telescope for Astronomy allow us to study the galaxy population down to m⋆ + 6 at the supercluster redshift. A dedicated spectroscopic survey with AAOmega on the Anglo-Australian Telescope provides a magnitude-limited sample of supercluster members with 80 per cent completeness at ˜m⋆ + 3. We derive the galaxy density across the whole area, demonstrating that all structures within this area are embedded in a single network of clusters, groups and filaments. The stellar mass density in the core of the SSC is always higher than 9 × 109 M⊙ Mpc-3, which is ˜40× the cosmic stellar mass density for galaxies in the local Universe. We find a new filamentary structure (˜7 Mpc long in projection) connecting the SSC core to the cluster A3559, as well as previously unidentified density peaks. We perform a weak-lensing analysis of the central 1 deg2 field of the survey obtaining for the central cluster A3558 a mass of M_{500}=7.63_{-3.40}^{+3.88}× 10^{14} M_{⊙}, in agreement with X-ray based estimates.

  18. A survey of ring galaxies in search of IMBHs

    NASA Astrophysics Data System (ADS)

    Wolter, Anna

    2015-08-01

    Recent results support the notion that the majority of Ultra Luminous X-ray sources are X-ray binary systems. In particular, the higher luminosity sources are the main reservoir in which to look for Intermediate Mass Black Holes (IMBH). IMBH have fundamental cosmological implications, as they are deemed to be the seeds of SuperMassive BHs, sources of pre-heating of the intergalactic medium and of fluctuation in the Near IR Cosmic Background. Although a few hundred ULXs and candidates are now known, there has never been a specific survey tailored to find these sources. Most of the host galaxies that contain a large number of ULXs have been selected because they are bright and famous, such e.g. the Cartwheel. The collection of ULXs in various catalogs is based on detections without assessment of non-detections. As a first step towards creating a statistical significant sample of ULXs, we have started a small but focused project to observe a sample of Ring Galaxies. Ring galaxies are particularly suitable for this study, as they generally have high SFR and are expected to host a relatively large number of ULXs. Due to the peculiar morphology of ring galaxies, detected point sources in the ring are very likely to be physically associated with the galaxy, reducing the problem of contamination from spurious sources. From formation model we expect them to have a low metallicity content, which favours the formation of high mass remnants, possibly from direct collapse.We have selected all the peculiar galaxies labelled as collisional rings with a spectroscopic redshift z<0.02 from the Arp & Madore `Catalogue of southern peculiar galaxies and associations'. This selection produces a sample of 12 galaxies which we have observed with Chandra and XMM-Newton. We will discuss the results of these observations and support for current models that propose low metallicity environments as the ideal cradle for ULXs. We will compare the results from this statistically selected sample

  19. The Bolocam Lockman Hole millimeter-wave galaxy survey

    NASA Astrophysics Data System (ADS)

    Laurent, G. T.

    2006-06-01

    This work presents results of a new deep (s 1.1mm ~= 1.4 mJy beam -1 ) 1.1 mm submillimeter galaxy survey using Bolocam, a millimeter-wavelength bolometer array camera designed for mapping large fields at fast scan rates, without chopping. A map, galaxy candidate list, and derived number counts are presented. The data were reduced using a custom software pipeline to remove correlated sky and instrument noise via a principal component analysis. Extensive simulations and jackknife tests were performed to confirm the robustness of our source candidates and estimate the effects of false detections, bias, and completeness. In total, 17 source candidates were detected at a significance > 3.0 s, with six expected false detections. From both our observed number counts and a fluctuation analysis, we estimate the underlying differential number count distribution of submillimeter galaxies and find it to be in general agreement with previous surveys. This work also presents 350 mm photometry of all 17 galaxy candidates detected in the Lockman Hole survey. Nine of the Bolocam galaxy candidates were detected at 350 mm and two new candidates were serendipitously detected at 350 mm (bringing the total in the literature detected in this way to three). Five of the galaxies have published spectroscopic redshifts, enabling investigation of the implied temperature ranges and a comparison of photometric redshift techniques. Because l = 350 mm lies near the spectral energy distribution peak for z [approximate] 2.5 thermally emitting galaxies, luminosities can be measured without extrapolating to the peak from detection wavelengths of l >= 850 mm. Characteristically, the galaxy luminosities lie in the range 1.0--1.2 × 10 13 [Special characters omitted.] , with dust temperatures in the range of 40 K to 70 K, depending on the choice of spectral index and wavelength of unit optical depth. The implied dust masses are 3--5 × 10 8 [Special characters omitted.] . We find that the far

  20. HUBBLE SURVEYS DYING STARS IN NEARBY GALAXY

    NASA Technical Reports Server (NTRS)

    2002-01-01

    From ground-based telescopes, the glowing gaseous debris surrounding dying, sun-like stars in a nearby galaxy, called the Large Magellanic Cloud, appear as small, shapeless dots of light. But through the 'eyes' of NASA's Hubble Space Telescope, these bright dots take on a variety of shapes, from round- to pinwheel-shaped clouds of gas. Using Hubble's Space Telescope Imaging Spectrograph, scientists probed the glowing gas surrounding 27 dying stars, called planetary nebulae, in the Large Magellanic Cloud. The observations represent the most detailed study of planetary nebulae outside the Milky Way. The six objects in the picture illustrate the assortment of planetary nebulae identified in the galaxy. SMP 16, 30, and 93 are examples of a bipolar nebula, twin lobes of gas projecting away from a dying star. SMP 10 has a pinwheel shape and is known as a 'point-symmetric' nebula. SMP 4 has an elliptical appearance, and SMP 27, consisting of four lobes of gas, is called a 'quadrupolar' nebula. The lines point to the objects' locations in the Large Magellanic Cloud. A ground-based observatory snapped the picture of this galaxy. In the pictures of the planetary nebulae, color corresponds to temperature. Blue represents hotter regions of the nebulae and red, cooler. Scientists are probing these illuminated stellar relics in our neighboring galaxy because they are at relatively the same distance - about 168,000 light-years -- from Earth. Knowing the distance to these objects allows scientists to compare their shapes and sizes, and precisely determine the brightness of their central stars. For this reason, even though these glowing remains of dying stars are about 50 times farther away than the stunning planetary nebulae photographed in the Milky Way, they are of invaluable importance. By sampling this population, scientists noticed that the bipolar nebulae are richer in some heavier elements, such as neon, than those with a more spherical shape. At the dawn of the universe

  1. HUBBLE SURVEYS DYING STARS IN NEARBY GALAXY

    NASA Technical Reports Server (NTRS)

    2002-01-01

    From ground-based telescopes, the glowing gaseous debris surrounding dying, sun-like stars in a nearby galaxy, called the Large Magellanic Cloud, appear as small, shapeless dots of light. But through the 'eyes' of NASA's Hubble Space Telescope, these bright dots take on a variety of shapes, from round- to pinwheel-shaped clouds of gas. Using Hubble's Space Telescope Imaging Spectrograph, scientists probed the glowing gas surrounding 27 dying stars, called planetary nebulae, in the Large Magellanic Cloud. The observations represent the most detailed study of planetary nebulae outside the Milky Way. The six objects in the picture illustrate the assortment of planetary nebulae identified in the galaxy. SMP 16, 30, and 93 are examples of a bipolar nebula, twin lobes of gas projecting away from a dying star. SMP 10 has a pinwheel shape and is known as a 'point-symmetric' nebula. SMP 4 has an elliptical appearance, and SMP 27, consisting of four lobes of gas, is called a 'quadrupolar' nebula. The lines point to the objects' locations in the Large Magellanic Cloud. A ground-based observatory snapped the picture of this galaxy. In the pictures of the planetary nebulae, color corresponds to temperature. Blue represents hotter regions of the nebulae and red, cooler. Scientists are probing these illuminated stellar relics in our neighboring galaxy because they are at relatively the same distance - about 168,000 light-years -- from Earth. Knowing the distance to these objects allows scientists to compare their shapes and sizes, and precisely determine the brightness of their central stars. For this reason, even though these glowing remains of dying stars are about 50 times farther away than the stunning planetary nebulae photographed in the Milky Way, they are of invaluable importance. By sampling this population, scientists noticed that the bipolar nebulae are richer in some heavier elements, such as neon, than those with a more spherical shape. At the dawn of the universe

  2. Probing neutrinos from Planck and forthcoming galaxy redshift surveys

    SciTech Connect

    Takeuchi, Yoshitaka; Kadota, Kenji E-mail: kadota.kenji@f.nagoya-u.jp

    2014-01-01

    We investigate how much the constraints on the neutrino properties can be improved by combining the CMB, the photometric and spectroscopic galaxy redshift surveys which include the CMB lensing, galaxy lensing tomography, galaxy clustering and redshift space distortion observables. We pay a particular attention to the constraint on the neutrino mass in view of the forthcoming redshift surveys such as the Euclid satellite and the LSST survey along with the Planck CMB lensing measurements. Combining the transverse mode information from the angular power spectrum and the longitudinal mode information from the spectroscopic survey with the redshift space distortion measurements can determine the total neutrino mass with the projected error of O(0.02) eV. Our analysis fixes the mass splittings among the neutrino species to be consistent with the neutrino oscillation data, and we accordingly study the sensitivity of our parameter estimations on the minimal neutrino mass. The cosmological measurement of the total neutrino mass can distinguish between the normal and inverted mass hierarchy scenarios if the minimal neutrino mass ∼<0.005 eV with the predicted 1–σ uncertainties taken into account.

  3. Wide Integral Field Infrared Spectroscopic Survey of Nearby Galaxies

    NASA Astrophysics Data System (ADS)

    Sivanandam, Suresh; Moon, Dae-Sik; Zaritsky, Dennis F.; Chou, Richard; Meyer, Elliot; Ma, Ke; Jarvis, Miranda; Eisner, Joshua A.

    2015-01-01

    We are constructing a novel infrared integral field spectrograph with a large field of view (~50'x20') that will be available on the Kitt Peak 90' Bok telescope this spring. This wide integral field infrared spectrograph (WIFIS) operates over two wavelength ranges, zJ-band (0.9-1.35 microns) and H-band (1.5-1.8 microns), and has moderate spectral resolving power, 3,000 in zJ-band and 2,200 in H-band, respectively. WIFIS' field-of-view is comparable to current optical integral field spectrographs that are carrying out large galaxy surveys, e.g. SAMI, CALIFA, and MaNGA. We are designing a large nearby galaxy survey to complement the data already been taken by these optical integral field spectroscopic surveys. The near-infrared window provides a sensitive probe of the initial mass functions of stellar populations, the OB stellar fractions in massive star forming regions, and the kinematics of and obscured star formation within merging systems. This will be the first large scale infrared integral field spectroscopic survey of nearby galaxies.

  4. THE CARNEGIE-IRVINE GALAXY SURVEY. II. ISOPHOTAL ANALYSIS

    SciTech Connect

    Li Zhaoyu; Ho, Luis C.; Barth, Aaron J.; Peng, Chien Y.

    2011-12-01

    The Carnegie-Irvine Galaxy Survey (CGS) is a comprehensive investigation of the physical properties of a complete, representative sample of 605 bright (B{sub T} {<=} 12.9 mag) galaxies in the southern hemisphere. This contribution describes the isophotal analysis of the broadband (BVRI) optical imaging component of the project. We pay close attention to sky subtraction, which is particularly challenging for some of the large galaxies in our sample. Extensive crosschecks with internal and external data confirm that our calibration and sky subtraction techniques are robust with respect to the quoted measurement uncertainties. We present a uniform catalog of one-dimensional radial profiles of surface brightness and geometric parameters, as well as integrated colors and color gradients. Composite profiles highlight the tremendous diversity of brightness distributions found in disk galaxies and their dependence on Hubble type. A significant fraction of S0 and spiral galaxies exhibit non-exponential profiles in their outer regions. We perform Fourier decomposition of the isophotes to quantify non-axisymmetric deviations in the light distribution. We use the geometric parameters, in conjunction with the amplitude and phase of the m = 2 Fourier mode, to identify bars and quantify their size and strength. Spiral arm strengths are characterized using the m = 2 Fourier profiles and structure maps. Finally, we utilize the information encoded in the m = 1 Fourier profiles to measure disk lopsidedness. The databases assembled here and in Paper I lay the foundation for forthcoming scientific applications of CGS.

  5. Galaxy Clustering in the Dark Energy Survey Science Verification Data

    NASA Astrophysics Data System (ADS)

    Ross, Ashley; Crocce, Martin; Dark Energy Survey Large Scale Structure Working Group Collaboration

    2015-04-01

    I present the results of a study of galaxy clustering in a flux-limited sample (iAB < 22 . 5) selected from the photometric Science Verification (SV) data of the Dark Energy Survey (DES), conducted by the DES large scale structure working group. The SV data provides science-quality images for more than 250 deg2 at the nominal DES depth (iAB ? 24). I will present the clustering analysis of this data, performed over five tomographic bins, with photometric redshifts, z, in the range 0.2 < z < 1.2. I will describe our work to identify and ameliorate systematics in the data set, which has allowed us to robustly measure the clustering amplitude of the galaxies in each tomographic bin. We test the relationship between the clustering of the galaxies and analytic predictions of the clustering of the dark matter, known as the bias relationship and determine the regime where it is described by a linear model I will present these results and compare them against a similar sample from the (previously) state-of-the-art CFHTLS, with which we find very good agreement. These results pave the way for exciting cosmological measurements to be made with future (larger) DES data sets and by combining the results with other probes such as CMB lensing and galaxy-galaxy lensing.

  6. A Snapshot Survey of The Most Massive Clusters of Galaxies

    NASA Astrophysics Data System (ADS)

    Ebeling, Harald

    2007-07-01

    We propose the continuation of our highly successful SNAPshot survey of a sample of 125 very X-ray luminous clusters in the redshift range 0.3-0.7. As demonstrated by the 25 snapshots obtained so far in Cycle14 and Cycle15 these systems frequently exhibit strong gravitational lensing as well as spectacular examples of violent galaxy interactions. The proposed observations will provide important constraints on the cluster mass distributions, the physical nature of galaxy-galaxy and galaxy-gas interactions in cluster cores, and a set of optically bright, lensed galaxies for further 8-10m spectroscopy. All of our primary science goals require only the detection and characterisation of high-surface-brightness features and are thus achievable even at the reduced sensitivity of WFPC2. Because of their high redshift and thus compact angular scale our target clusters are less adversely affected by the smaller field of view of WFPC2 than more nearby systems. Acknowledging the broad community interest in this sample we waive our data rights for these observations. Due to a clerical error at STScI our approved Cycle15 SNAP program was barred from execution for 3 months and only 6 observations have been performed to date - reinstating this SNAP at Cycle16 priority is of paramount importance to reach meaningful statistics.

  7. Redshifts for 2410 Galaxies in the Century Survey Region

    NASA Astrophysics Data System (ADS)

    Wegner, Gary; Thorstensen, John R.; Kurtz, Michael J.; Brown, Warren R.; Fabricant, Daniel G.; Geller, Margaret J.; Huchra, John P.; Marzke, Ronald O.; Sakai, Shoko

    2001-12-01

    The Century Survey strip covers 102 deg2 within the limits 8h5<=α<=16h5, 29.0d<=δ<=30.0d, equinox B1950.0. The strip passes through the Corona Borealis supercluster and the outer region of the Coma cluster. Within the Century Survey region, we have measured 2410 redshifts that constitute four overlapping complete redshift surveys: (1) 1728 galaxies with Kron-Cousins Rph<=16.13 covering the entire strip, (2) 507 galaxies with Rph<=16.4 in right ascension range 8h32m<=α<=10 h45m, equinox B1950.0, (3) 1251 galaxies with absorption- and K-corrected RCCDc<=16.2 (where ``c'' indicates ``corrected'') covering the right ascension range 8h5<=α<=13h5, equinox B1950.0, and (4) 1255 galaxies with absorption- and K-corrected VCCDc<=16.7 also covering the right ascension range 8h5<=α<=13h5, equinox B1950.0. All these redshift samples are more than 98% complete to the specified magnitude limit. We derived samples 1 and 2 from scans of the POSS1 red (E) plates calibrated with CCD photometry. We derived samples 3 and 4 from deep V and R CCD images covering the entire region. We include coarse morphological types for all the galaxies in sample 1. The distribution of (V-R)CCD for each type corresponds appropriately with the classification. Work reported here is based partly on observations obtained at the Michigan-Dartmouth-MIT Observatory.

  8. A survey of satellite galaxies around NGC 4258

    SciTech Connect

    Spencer, Meghin; Loebman, Sarah; Yoachim, Peter

    2014-06-20

    We conduct a survey of satellite galaxies around the nearby spiral NGC 4258 by combining spectroscopic observations from the Apache Point Observatory 3.5 m telescope with Sloan Digital Sky Survey (SDSS) spectra. New spectroscopy is obtained for 15 galaxies. Of the 47 observed objects, we categorize 8 of them as probable satellites, 8 as possible satellites, and 17 as unlikely to be satellites. We do not speculate on the membership of the remaining 14 galaxies due to a lack of velocity and distance information. Radially integrating our best-fit NFW profile for NGC 4258 yields a total mass of 1.8 × 10{sup 12} M {sub ☉} within 200 kpc. We find that the angular distribution of the satellites appears to be random, and not preferentially aligned with the disk of NGC 4258. In addition, many of the probable satellite galaxies have blue u–r colors and appear to be star-forming irregulars in SDSS images; this stands in contrast to the low number of blue satellites in the Milky Way and M31 systems at comparable distances.

  9. An HI Survey of Extremely Isolated Early-Type Galaxies

    NASA Astrophysics Data System (ADS)

    Ashley, Trisha L.; Marcum, Pamela M.; Fanelli, Michael N.

    2016-06-01

    We present the results of an HI survey of extremely isolated early-type galaxies (IEGs) using the NRAO Green Bank Telescope (GBT). The systems studied here, drawn from Marcum et al. (2004) and Fuse et al. (2012), were selected for their isolation from companions (MV < -16.5) within a distance of at least 2.5 Mpc. Previous optical imaging/spectroscopy investigations of these galaxies found a higher percentage of the sample exhibiting recent or ongoing star formation, relative to their counterparts in higher density environments. The HI masses and kinematics derived from the presented data provide a characterization of the IEGs’ gas reservoirs, which may be fueling their star formation. Initial findings from the HI survey, the first comprehensive assessment of neutral gas content within and around such systems, indicate at least 50% of the observed isolated early-type galaxies have detectable HI gas. We also find that a linear relationship between B‑V and log(MHI/LB) provides a method for predicting H I mass in non-cluster early-type galaxies.

  10. THE CARNEGIE-IRVINE GALAXY SURVEY. III. THE THREE-COMPONENT STRUCTURE OF NEARBY ELLIPTICAL GALAXIES

    SciTech Connect

    Huang, Song; Ho, Luis C.; Peng, Chien Y.; Li, Zhao-Yu; Barth, Aaron J.

    2013-03-20

    Motivated by recent developments in our understanding of the formation and evolution of massive galaxies, we explore the detailed photometric structure of a representative sample of 94 bright, nearby elliptical galaxies, using high-quality optical images from the Carnegie-Irvine Galaxy Survey. The sample spans a range of environments and stellar masses, from M{sub *} = 10{sup 10.2} to 10{sup 12.0} M{sub Sun }. We exploit the unique capabilities of two-dimensional image decomposition to explore the possibility that local elliptical galaxies may contain photometrically distinct substructure that can shed light on their evolutionary history. Compared with the traditional one-dimensional approach, these two-dimensional models are capable of consistently recovering the surface brightness distribution and the systematic radial variation of geometric information at the same time. Contrary to conventional perception, we find that the global light distribution of the majority ({approx}>75%) of elliptical galaxies is not well described by a single Sersic function. Instead, we propose that local elliptical galaxies generically contain three subcomponents: a compact (R{sub e} {approx}< 1 kpc) inner component with luminosity fraction f Almost-Equal-To 0.1-0.15; an intermediate-scale (R{sub e} Almost-Equal-To 2.5 kpc) middle component with f Almost-Equal-To 0.2-0.25; and a dominant (f = 0.6), extended (R{sub e} Almost-Equal-To 10 kpc) outer envelope. All subcomponents have average Sersic indices n Almost-Equal-To 1-2, significantly lower than the values typically obtained from single-component fits. The individual subcomponents follow well-defined photometric scaling relations and the stellar mass-size relation. We discuss the physical nature of the substructures and their implications for the formation of massive elliptical galaxies.

  11. ULTRALUMINOUS INFRARED GALAXIES IN THE WISE AND SDSS SURVEYS

    SciTech Connect

    Su, Shanshan; Kong, Xu; Li, Jinrong; Fang, Guanwen E-mail: xkong@ustc.edu.cn

    2013-11-20

    In this paper, we present a large catalog of 419 Ultraluminous infrared galaxies (ULIRGs), carefully selected from the Wide-field Infrared Survey Explorer mid-infrared data and the Sloan Digital Sky Survey eighth data release, and classify them into three subsamples, based on their emission line properties: H II-like ULIRGs, Seyfert 2 ULIRGs, and composite ULIRGs. We apply our new efficient spectral synthesis technique, which is based on mean field approach to Bayesian independent component analysis (MF-ICA) method, to the galaxy integrated spectra. We also analyze the stellar population properties, including percentage contribution, stellar age, and stellar mass, for these three types of ULIRGs, and explore the evolution among them. We find no significant difference between the properties of stellar populations in ULIRGs with or without active galactic nucleus components. Our results suggest that there is no evolutionary link among these three type ULIRGs.

  12. Reconstructing the integrated Sachs-Wolfe map with galaxy surveys

    NASA Astrophysics Data System (ADS)

    Muir, Jessica; Huterer, Dragan

    2016-08-01

    The integrated Sachs-Wolfe (ISW) effect is a large-angle modulation of the cosmic microwave background (CMB), generated when CMB photons traverse evolving potential wells associated with large scale structure (LSS). Recent efforts have been made to reconstruct maps of the ISW signal using information from surveys of galaxies and other LSS tracers, but investigation into how survey systematics affect their reliability has so far been limited. Using simulated ISW and LSS maps, we study the impact of galaxy survey properties and systematic errors on the accuracy of a reconstructed ISW signal. We find that systematics that affect the observed distribution of galaxies along the line of sight, such as photo-z and bias-evolution related errors, have a relatively minor impact on reconstruction quality. In contrast, however, we find that direction-dependent calibration errors can be very harmful. Specifically, we find that, in order to avoid significant degradation of our reconstruction quality statistics, direction-dependent number density fluctuations due to systematics must be controlled so that their variance is smaller than 10-6 (which corresponds to a 0.1% calibration). Additionally, we explore the implications of our results for attempts to use reconstructed ISW maps to shed light on the origin of large-angle CMB alignments. We find that there is only a weak correlation between the true and reconstructed angular momentum dispersion, which quantifies alignment, even for reconstructed ISW maps which are fairly accurate overall.

  13. THE DEEP2 GALAXY REDSHIFT SURVEY: THE VORONOI-DELAUNAY METHOD CATALOG OF GALAXY GROUPS

    SciTech Connect

    Gerke, Brian F.; Newman, Jeffrey A.; Davis, Marc; Coil, Alison L.; Cooper, Michael C.; Dutton, Aaron A.; Faber, S. M.; Guhathakurta, Puragra; Koo, David C.; Phillips, Andrew C.; Noeske, Kai; Rosario, David J.; Weiner, Benjamin J.; Willmer, Christopher N. A.; Yan, Renbin

    2012-05-20

    We present a public catalog of galaxy groups constructed from the spectroscopic sample of galaxies in the fourth data release from the Deep Extragalactic Evolutionary Probe 2 (DEEP2) Galaxy Redshift Survey, including the Extended Groth Strip (EGS). The catalog contains 1165 groups with two or more members in the EGS over the redshift range 0 < z < 1.5 and 1295 groups at z > 0.6 in the rest of DEEP2. Twenty-five percent of EGS galaxies and fourteen percent of high-z DEEP2 galaxies are assigned to galaxy groups. The groups were detected using the Voronoi-Delaunay method (VDM) after it has been optimized on mock DEEP2 catalogs following similar methods to those employed in Gerke et al. In the optimization effort, we have taken particular care to ensure that the mock catalogs resemble the data as closely as possible, and we have fine-tuned our methods separately on mocks constructed for the EGS and the rest of DEEP2. We have also probed the effect of the assumed cosmology on our inferred group-finding efficiency by performing our optimization on three different mock catalogs with different background cosmologies, finding large differences in the group-finding success we can achieve for these different mocks. Using the mock catalog whose background cosmology is most consistent with current data, we estimate that the DEEP2 group catalog is 72% complete and 61% pure (74% and 67% for the EGS) and that the group finder correctly classifies 70% of galaxies that truly belong to groups, with an additional 46% of interloper galaxies contaminating the catalog (66% and 43% for the EGS). We also confirm that the VDM catalog reconstructs the abundance of galaxy groups with velocity dispersions above {approx}300 km s{sup -1} to an accuracy better than the sample variance, and this successful reconstruction is not strongly dependent on cosmology. This makes the DEEP2 group catalog a promising probe of the growth of cosmic structure that can potentially be used for cosmological tests.

  14. Mapping Nearby Galaxies at APO: The MaNGA IFU Galaxy Survey

    NASA Astrophysics Data System (ADS)

    Law, David R.; MaNGA Team

    2014-01-01

    MaNGA is a new survey that will begin in August 2014 as part of SDSS-IV with the aim of obtaining integral-field spectroscopy for an unprecedented sample of 10,000 nearby galaxies. MaNGA's key goals are to understand the "life cycle" of present day galaxies from imprinted clues of their birth and assembly, through their ongoing growth via star formation and merging, to their death from quenching at late times. To achieve these goals, MaNGA will channel the impressive capabilities of the SDSS-III BOSS spectrographs in a fundamentally new direction by marshaling the unique power of 2D spectroscopy. MaNGA will deploy 17 pluggable Integral Field Units (IFUs) made by grouping fibers into hexagonal bundles ranging from 19 to 127 fibers each. The spectra obtained by MaNGA will cover the wavelength range 3600-10,000 Angstroms (with a velocity resolution of ~ 60 km/s) and will characterize the internal composition and the dynamical state of a sample of 10,000 galaxies with stellar masses greater than 10^9 Msun and an average redshift of z ~ 0.03. Such IFU observations enable a leap forward because they provide an added dimension to the information available for each galaxy. MaNGA will provide two-dimensional maps of stellar velocity and velocity dispersion, mean stellar age and star formation history, stellar metallicity, element abundance ratio, stellar mass surface density, ionized gas velocity, ionized gas metallicity, star formation rate, and dust extinction for a statistically powerful sample. This legacy dataset will address urgent questions in our understanding of galaxy formation, including 1) The formation history of galaxy subcomponents, including the disk, bulge, and dark matter halo, 2) The nature of present-day galaxy growth via merging and gas accretion, and 3) The processes responsible for terminating star formation in galaxies. Finally, MaNGA will also play a vital role in the coming era of advanced IFU instrumentation, serving as the low-z anchor for

  15. Early-type galaxies in the Chandra cosmos survey

    SciTech Connect

    Civano, F.; Fabbiano, G.; Kim, D.-W.; Paggi, A.; Elvis, M.; Pellegrini, S.; Feder, R.

    2014-07-20

    We study a sample of 69 X-ray detected early-type galaxies (ETGs), selected from the Chandra COSMOS survey, to explore the relation between the X-ray luminosity of hot gaseous halos (L{sub X,{sub gas}}) and the integrated stellar luminosity (L{sub K} ) of the galaxies, in a range of redshift extending out to z = 1.5. In the local universe, a tight, steep relationship has been established between these two quantities (L{sub X,gas}∼L{sub K}{sup 4.5}), suggesting the presence of largely virialized halos in X-ray luminous systems. We use well-established relations from the study of local universe ETGs, together with the expected evolution of the X-ray emission, to subtract the contribution of low-mass X-ray binary populations from the X-ray luminosity of our sample. Our selection minimizes the presence of active galactic nuclei (AGNs), yielding a sample representative of normal passive COSMOS ETGs; therefore, the resulting luminosity should be representative of gaseous halos, although we cannot exclude other sources such as obscured AGNs or enhanced X-ray emission connected with embedded star formation in the higher-z galaxies. We find that most of the galaxies with estimated L{sub X} < 10{sup 42} erg s{sup –1} and z < 0.55 follow the L{sub X,{sub gas}}-L{sub K} relation of local universe ETGs. For these galaxies, the gravitational mass can be estimated with a certain degree of confidence from the local virial relation. However, the more luminous (10{sup 42} erg s{sup –1} galaxies present significantly larger scatter; these galaxies also tend to have younger stellar ages. The divergence from the local L{sub X,{sub gas}}-L{sub K} relation in these galaxies implies significantly enhanced X-ray emission up to a factor of 100 larger than predicted from the local relation. We discuss the implications of this result for the presence of hidden AGNs, and the evolution of hot halos, in nuclear and star formation

  16. Cosmology from large scale galaxy clustering and galaxy-galaxy lensing with Dark Energy Survey Science Verification data

    DOE PAGES

    Kwan, J.

    2016-10-05

    Here, we present cosmological constraints from the Dark Energy Survey (DES) using a combined analysis of angular clustering of red galaxies and their cross-correlation with weak gravitational lensing of background galaxies. We use a 139 square degree contiguous patch of DES data from the Science Verification (SV) period of observations. Using large scale measurements, we constrain the matter density of the Universe as Ωm = 0.31 ± 0.09 and the clustering amplitude of the matter power spectrum as σ8 = 0.74 ± 0.13 after marginalizing over seven nuisance parameters and three additional cosmological parameters. This translates into S8 Ξ σ8more » (Ωm/0.3)0.16 = 0.74 ± 0.12 for our fiducial lens redshift bin at 0.35 < z < 0.5, while S8 = 0.78 ± 0.09 using two bins over the range 0.2 < z < 0.5. We study the robustness of the results under changes in the data vectors, modelling and systematics treatment, including photometric redshift and shear calibration uncertainties, and find consistency in the derived cosmological parameters. We show that our results are consistent with previous cosmological analyses from DES and other data sets and conclude with a joint analysis of DES angular clustering and galaxy-galaxy lensing with Planck CMB data, Baryon Accoustic Oscillations and Supernova type Ia measurements.« less

  17. Cosmology from large scale galaxy clustering and galaxy-galaxy lensing with Dark Energy Survey Science Verification data

    NASA Astrophysics Data System (ADS)

    Kwan, J.; Sánchez, C.; Clampitt, J.; Blazek, J.; Crocce, M.; Jain, B.; Zuntz, J.; Amara, A.; Becker, M. R.; Bernstein, G. M.; Bonnett, C.; DeRose, J.; Dodelson, S.; Eifler, T. F.; Gaztanaga, E.; Giannantonio, T.; Gruen, D.; Hartley, W. G.; Kacprzak, T.; Kirk, D.; Krause, E.; MacCrann, N.; Miquel, R.; Park, Y.; Ross, A. J.; Rozo, E.; Rykoff, E. S.; Sheldon, E.; Troxel, M. A.; Wechsler, R. H.; Abbott, T. M. C.; Abdalla, F. B.; Allam, S.; Benoit-Lévy, A.; Brooks, D.; Burke, D. L.; Rosell, A. Carnero; Carrasco Kind, M.; Cunha, C. E.; D'Andrea, C. B.; da Costa, L. N.; Desai, S.; Diehl, H. T.; Dietrich, J. P.; Doel, P.; Evrard, A. E.; Fernandez, E.; Finley, D. A.; Flaugher, B.; Fosalba, P.; Frieman, J.; Gerdes, D. W.; Gruendl, R. A.; Gutierrez, G.; Honscheid, K.; James, D. J.; Jarvis, M.; Kuehn, K.; Lahav, O.; Lima, M.; Maia, M. A. G.; Marshall, J. L.; Martini, P.; Melchior, P.; Mohr, J. J.; Nichol, R. C.; Nord, B.; Plazas, A. A.; Reil, K.; Romer, A. K.; Roodman, A.; Sanchez, E.; Scarpine, V.; Sevilla-Noarbe, I.; Smith, R. C.; Soares-Santos, M.; Sobreira, F.; Suchyta, E.; Swanson, M. E. C.; Tarle, G.; Thomas, D.; Vikram, V.; Walker, A. R.

    2016-10-01

    We present cosmological constraints from the Dark Energy Survey (DES) using a combined analysis of angular clustering of red galaxies and their cross-correlation with weak gravitational lensing of background galaxies. We use a 139 square degree contiguous patch of DES data from the Science Verification (SV) period of observations. Using large scale measurements, we constrain the matter density of the Universe as Ωm = 0.31 ± 0.09 and the clustering amplitude of the matter power spectrum as σ8 = 0.74 ± 0.13 after marginalizing over seven nuisance parameters and three additional cosmological parameters. This translates into S8 ≡ σ8(Ωm/0.3)0.16 = 0.74 ± 0.12 for our fiducial lens redshift bin at 0.35 galaxy-galaxy lensing with Planck CMB data, Baryon Accoustic Oscillations and Supernova type Ia measurements.

  18. DGSAT: Dwarf Galaxy Survey with Amateur Telescopes. I. Discovery of low surface brightness systems around nearby spiral galaxies

    NASA Astrophysics Data System (ADS)

    Javanmardi, B.; Martinez-Delgado, D.; Kroupa, P.; Henkel, C.; Crawford, K.; Teuwen, K.; Gabany, R. J.; Hanson, M.; Chonis, T. S.; Neyer, F.

    2016-04-01

    Context. We introduce the Dwarf Galaxy Survey with Amateur Telescopes (DGSAT) project and report the discovery of eleven low surface brightness (LSB) galaxies in the fields of the nearby galaxies NGC 2683, NGC 3628, NGC 4594 (M 104), NGC 4631, NGC 5457 (M 101), and NGC 7814. Aims: The DGSAT project aims to use the potential of small-sized telescopes to probe LSB features around large galaxies and to increase the sample size of the dwarf satellite galaxies in the Local Volume. Methods: Using long exposure images, fields of the target spiral galaxies are explored for extended LSB objects. After identifying dwarf galaxy candidates, their observed properties are extracted by fitting models to their light profiles. Results: We find three, one, three, one, one, and two new LSB galaxies in the fields of NGC 2683, 3628, 4594, 4631, 5457, and 7814, respectively. In addition to the newly found galaxies, we analyse the structural properties of nine already known galaxies. All of these 20 dwarf galaxy candidates have effective surface brightnesses in the range 25.3 ≲ μe ≲ 28.8 mag arcsec-2 and are fit with Sersic profiles with indices n ≲ 1. Assuming that they are in the vicinity of the above mentioned massive galaxies, their r-band absolute magnitudes, their effective radii, and their luminosities are in the ranges -15.6 ≲ Mr ≲ -7.8, 160 pc ≲ Re ≲ 4.1 kpc, and 0.1 × 106 ≲ (L/L⊙)r ≲ 127 × 106, respectively. To determine whether these LSB galaxies are indeed satellites of the above mentioned massive galaxies, their distances need to be determined via further observations. Conclusions: Using small telescopes, we are readily able to detect LSB galaxies with similar properties to the known dwarf galaxies of the Local Group.

  19. The Secret Lives Of Galaxies Unveiled In Deep Survey

    NASA Astrophysics Data System (ADS)

    2003-06-01

    Two of NASA's Great Observatories, bolstered by the largest ground-based telescopes around the world, are beginning to harvest new clues to the origin and evolution of galaxies. It's a bit like finding a family scrapbook containing snapshots that capture the lives of family members from infancy through adolescence to adulthood. "This is the first time the cosmic tale of how galaxies build themselves has been traced reliably to such early times in the universe's life," said Mauro Giavalisco, head of the Hubble Space Telescope (HST) portion of the survey, and research astronomer at the Space Telescope Science Institute (STScI) in Baltimore. The HST has joined forces with the Chandra X-ray Observatory to survey a relatively broad swath of sky encompassing tens of thousands of galaxies stretching far back into time. The Space Infrared Telescope Facility (SIRTF), scheduled for launch in August, will soon join this unprecedented survey. Called the Great Observatories Origins Deep Survey (GOODS), astronomers are studying galaxy formation and evolution over a wide range of distances and ages. The project is tracing the assembly history of galaxies, the evolution of their stellar populations, and the gusher of energy from star formation and active nuclei powered by immense black holes. HST astronomers report the sizes of galaxies clearly increase continuously from the time the universe was about 1 billion years old to an age of 6 billion years. This is approximately half the current age of the universe, 13.7 billion years. GOODS astronomers also find the star birth rate rose mildly, by about a factor of three, between the time the universe was about one billion years old and 1.5 billion years old, and remained high until about 7 billion years ago, when it quickly dropped to one-tenth the earlier "baby boomer" rate. This is further evidence major galaxy building trailed off when the universe was about half its current age. GOODS Chandra Deep Fields South Chandra Deep Field

  20. The Secret Lives Of Galaxies Unveiled In Deep Survey

    NASA Astrophysics Data System (ADS)

    2003-06-01

    Two of NASA's Great Observatories, bolstered by the largest ground-based telescopes around the world, are beginning to harvest new clues to the origin and evolution of galaxies. It's a bit like finding a family scrapbook containing snapshots that capture the lives of family members from infancy through adolescence to adulthood. "This is the first time the cosmic tale of how galaxies build themselves has been traced reliably to such early times in the universe's life," said Mauro Giavalisco, head of the Hubble Space Telescope (HST) portion of the survey, and research astronomer at the Space Telescope Science Institute (STScI) in Baltimore. The HST has joined forces with the Chandra X-ray Observatory to survey a relatively broad swath of sky encompassing tens of thousands of galaxies stretching far back into time. The Space Infrared Telescope Facility (SIRTF), scheduled for launch in August, will soon join this unprecedented survey. Called the Great Observatories Origins Deep Survey (GOODS), astronomers are studying galaxy formation and evolution over a wide range of distances and ages. The project is tracing the assembly history of galaxies, the evolution of their stellar populations, and the gusher of energy from star formation and active nuclei powered by immense black holes. HST astronomers report the sizes of galaxies clearly increase continuously from the time the universe was about 1 billion years old to an age of 6 billion years. This is approximately half the current age of the universe, 13.7 billion years. GOODS astronomers also find the star birth rate rose mildly, by about a factor of three, between the time the universe was about one billion years old and 1.5 billion years old, and remained high until about 7 billion years ago, when it quickly dropped to one-tenth the earlier "baby boomer" rate. This is further evidence major galaxy building trailed off when the universe was about half its current age. GOODS Chandra Deep Fields South Chandra Deep Field

  1. A VIRUS-P Survey of Galaxy Clusters to Find Faint Lyα-emitting Galaxies

    NASA Astrophysics Data System (ADS)

    McLinden, Emily; Finkelstein, S. L.; Siana, B. D.; Alavi, A.

    2014-01-01

    The VIRUS-P instrument on the 2.7m telescope at the McDonald Observatory was originally built as a prototype of the larger VIRUS instrument that will be used for HETDEX. We demonstrate that this multi-fiber, optical integral field unit spectrograph can be efficiently used to detect faint Lyα-emitting galaxies (LAEs) at intermediate redshift (z = 2-3) with the aid of gravitational lensing from galaxy clusters. The bulk z=2-3 LAEs to date have been discovered with narrowband imaging campaigns, which are highly efficient only at selecting L > L_star galaxies and only over a narrow redshift slice. By making use of gravitational lensing, however, we are able to observe intrinsically very faint galaxies that only appear to have brightnesses ≥ L_star. Gravitationally lensed faint LAEs, such as our sample from VIRUS-P, allow us to go fainter than existing narrowband surveys and therefore allow for better constraints at the faint end of the Lyα luminosity function at these intermediate redshifts.

  2. The 2dF Galaxy Redshift Survey: the number and luminosity density of galaxies

    NASA Astrophysics Data System (ADS)

    Cross, Nicholas; Driver, Simon P.; Couch, Warrick; Baugh, Carlton M.; Bland-Hawthorn, Joss; Bridges, Terry; Cannon, Russell; Cole, Shaun; Colless, Matthew; Collins, Chris; Dalton, Gavin; Deeley, Kathryn; De Propris, Roberto; Efstathiou, George; Ellis, Richard S.; Frenk, Carlos S.; Glazebrook, Karl; Jackson, Carole; Lahav, Ofer; Lewis, Ian; Lumsden, Stuart; Maddox, Steve; Madgwick, Darren; Moody, Stephen; Norberg, Peder; Peacock, John A.; Peterson, Bruce A.; Price, Ian; Seaborne, Mark; Sutherland, Will; Tadros, Helen; Taylor, Keith

    2001-07-01

    We present the bivariate brightness distribution (BBD) for the 2dF Galaxy Redshift Survey (2dFGRS) based on a preliminary subsample of 45000 galaxies. The BBD is an extension of the galaxy luminosity function, incorporating surface brightness information. It allows the measurement of the local luminosity density, jB, and of the galaxy luminosity and surface brightness distributions, while accounting for surface brightness selection biases. The recovered 2dFGRS BBD shows a strong luminosity-surface brightness relation MB~(2.4+/-0.51.5)μe], providing a new constraint for galaxy formation models. In terms of the number density, we find that the peak of the galaxy population lies at MB>=-16.0mag. Within the well-defined selection limits (-24galaxies (i.e., 90 per cent of the luminosity density is contained within -22.5galaxies are rare. The final value we derive for the local luminosity density, inclusive of surface brightness corrections, is jB=2.49+/- 0.20×108h100LsolarMpc- 3. Representative Schechter function parameters are M*=-19.75+/-0.05, φ*=2.02+/-0.02×10-2 and α=-1.09+/-0.03. Finally, we note that extending the conventional methodology to incorporate surface brightness selection effects has resulted in an increase in the luminosity density of ~37 per cent. Hence surface brightness selection effects would appear to explain much of the discrepancy between previous estimates of the local luminosity density.

  3. An Open-Source Galaxy Redshift Survey Simulator for next-generation Large Scale Structure Surveys

    NASA Astrophysics Data System (ADS)

    Seijak, Uros

    Galaxy redshift surveys produce three-dimensional maps of the galaxy distribution. On large scales these maps trace the underlying matter fluctuations in a relatively simple manner, so that the properties of the primordial fluctuations along with the overall expansion history and growth of perturbations can be extracted. The BAO standard ruler method to measure the expansion history of the universe using galaxy redshift surveys is thought to be robust to observational artifacts and understood theoretically with high precision. These same surveys can offer a host of additional information, including a measurement of the growth rate of large scale structure through redshift space distortions, the possibility of measuring the sum of neutrino masses, tighter constraints on the expansion history through the Alcock-Paczynski effect, and constraints on the scale-dependence and non-Gaussianity of the primordial fluctuations. Extracting this broadband clustering information hinges on both our ability to minimize and subtract observational systematics to the observed galaxy power spectrum, and our ability to model the broadband behavior of the observed galaxy power spectrum with exquisite precision. Rapid development on both fronts is required to capitalize on WFIRST's data set. We propose to develop an open-source computational toolbox that will propel development in both areas by connecting large scale structure modeling and instrument and survey modeling with the statistical inference process. We will use the proposed simulator to both tailor perturbation theory and fully non-linear models of the broadband clustering of WFIRST galaxies and discover novel observables in the non-linear regime that are robust to observational systematics and able to distinguish between a wide range of spatial and dynamic biasing models for the WFIRST galaxy redshift survey sources. We have demonstrated the utility of this approach in a pilot study of the SDSS-III BOSS galaxies, in which we

  4. Super Star Clusters in Luminous Infrared Galaxies: the SUNBIRD Survey

    NASA Astrophysics Data System (ADS)

    Väisänen, P.; Randriamanakoto, Z.; Escala, A.; Kankare, E.; Kniazev, A.; Kotilainen, J. K.; Mattila, S.; Ramphul, R.; Ryder, S.; Tekola, A.

    2014-09-01

    We summarize recent results from an Adaptive Optics (AO) imaging survey of 40 Luminous IR Galaxies (LIRGs). We have constructed the first statistically significant sample of Luminosity Functions (LFs) of Super Star Clusters (SSCs) in the near-IR, and find evidence that the LF slopes in LIRGs are shallower than in more quiescent spiral galaxies. Distance and blending effects were investigated in detail paving the way for SSC studies further out than done previously. We have also correlated the luminosities of the brightest clusters with the star formation rates of the hosts and find that the characteristics of the relation suggest an underlying physical driver rather than solely a size-of-sample effect. Finally we present early results of using SSC age and mass properties to trace the histories of the target LIRG systems.

  5. Spatial density fluctuations and selection effects in galaxy redshift surveys

    SciTech Connect

    Labini, Francesco Sylos; Tekhanovich, Daniil; Baryshev, Yurij V. E-mail: d.tekhanovich@spbu.ru

    2014-07-01

    One of the main problems of observational cosmology is to determine the range in which a reliable measurement of galaxy correlations is possible. This corresponds to determining the shape of the correlation function, its possible evolution with redshift and the size and amplitude of large scale structures. Different selection effects, inevitably entering in any observation, introduce important constraints in the measurement of correlations. In the context of galaxy redshift surveys selection effects can be caused by observational techniques and strategies and by implicit assumptions used in the data analysis. Generally all these effects are taken into account by using pair-counting algorithms to measure two-point correlations. We review these methods stressing that they are based on the a-priori assumption that galaxy distribution is spatially homogeneous inside a given sample. We show that, when this assumption is not satisfied by the data, results of the correlation analysis are affected by finite size effects. In order to quantify these effects, we introduce a new method based on the computation of the gradient of galaxy counts along tiny cylinders. We show, by using artificial homogeneous and inhomogeneous point distributions, that this method identifies redshift dependent selection effects and disentangles them from the presence of large scale density fluctuations. We then apply this new method to several redshift catalogs and we find evidence that galaxy distribution, in those samples where selection effects are small enough, is characterized by power-law correlations with exponent γ=0.9 up to 20 Mpc/h followed by a change of slope that, in the range 20–100 Mpc/h, corresponds to a power-law exponent γ=0.25. Whether a crossover to spatial uniformity occurs at ∼ 100 Mpc/h or larger scales cannot be clarified by the present data.

  6. A Snapshot Survey of The Most Massive Clusters of Galaxies

    NASA Astrophysics Data System (ADS)

    Ebeling, Harald

    2010-09-01

    We propose the continuation of our highly successful HST/ACS SNAPshot survey of a sample of 123 very X-ray luminous clusters in the redshift range 0.3-0.7, detected and compiled by the MACS cluster survey. As demonstrated by dedicated HST observations of the 12 most distant MACS clusters {GO-09722} as well as by the MACS SNAPshots of an additional 25 obtained with ACS so far in Cycles 14 and 15, these systems frequently exhibit strong gravitational lensing as well as spectacular examples of violent galaxy evolution. A large number of additional MACS SNAPs have since been obtained with WFPC2, leading to the discovery of several more powerful cluster lenses. The dramatic loss, however, of depth, field-of-view, and angular resolution compared to ACS led to significantly reduced scientific returns, underlining the need for ACS for this project. The proposed observations will provide important constraints on the cluster mass distributions, on the physical nature of !galaxy-galaxy and galaxy-gas interactions in cluster cores, and will yield a set of optically bright, lensed galaxies for further 8-10m spectroscopy. For those of our targets with existing ACS SNAPshot images, we propose SNAPshots in the WFC3 F110W and F140W passbands to obtain colour information that will greatly improve the secure identification of multiple-image systems and may, in the form of F606W or F814W dropouts, lead to the lensing-enabled discovery of very distant galaxies at z>5. Acknowledging the broad community interest in this sample {16 of the 25 targets of the approved MCT cluster program are MACS discoveries} we waive our data rights for these observations.This proposal is an updated and improved version of our successful Cycle 15 proposal of the same title. Alas, SNAP-10875 collected only six snapshots in the F606W or F814W passbands, due to, first, a clerical error at STScI which caused the program to be barred from execution for four months and, ultimately, the failure of ACS. With ACS

  7. THE SPITZER HIGH-REDSHIFT RADIO GALAXY SURVEY

    SciTech Connect

    De Breuck, Carlos; Galametz, Audrey; Vernet, Joel; Seymour, Nick; Stern, Daniel; Eisenhardt, P. R. M.; Willner, S. P.; Fazio, G. G.; Lacy, Mark; Rettura, Alessandro; Rocca-Volmerange, Brigitte

    2010-12-10

    We present results from a comprehensive imaging survey of 70 radio galaxies at redshifts 1 < z < 5.2 using all three cameras on board the Spitzer Space Telescope. The resulting spectral energy distributions unambiguously show a stellar population in 46 sources and hot dust emission associated with the active nucleus in 59. Using a new rest-frame S{sub 3{sub {mu}m}}/S{sub 1.6{sub {mu}m}} versus S{sub 5{sub {mu}m}}/S{sub 3{sub {mu}m}} criterion, we identify 42 sources where the rest-frame 1.6 {mu}m emission from the stellar population can be measured. For these radio galaxies, the median stellar mass is high, 2 x 10{sup 11} M{sub sun}, and remarkably constant within the range 1 < z < 3. At z>3, there is tentative evidence for a factor of two decrease in stellar mass. This suggests that radio galaxies have assembled the bulk of their stellar mass by z {approx} 3, but confirmation by more detailed decomposition of stellar and active galactic nucleus (AGN) emission is needed. The rest-frame 500 MHz radio luminosities are only marginally correlated with stellar mass but are strongly correlated with the rest-frame 5 {mu}m hot dust luminosity. This suggests that the radio galaxies have a large range of Eddington ratios. We also present new Very Large Array 4.86 and 8.46 GHz imaging of 14 radio galaxies and find that radio core dominance-an indicator of jet orientation-is strongly correlated with hot dust luminosity. While all of our targets were selected as narrow-lined, type 2 AGNs, this result can be understood in the context of orientation-dependent models if there is a continuous distribution of orientations from obscured type 2 to unobscured type 1 AGNs rather than a clear dichotomy. Finally, four radio galaxies have nearby (<6'') companions whose mid-IR colors are suggestive of their being AGNs. This may indicate an association between radio galaxy activity and major mergers.

  8. Mass and galaxy distributions of four massive galaxy clusters from Dark Energy Survey Science Verification data

    DOE PAGES

    Melchior, P.; Suchyta, E.; Huff, E.; Hirsch, M.; Kacprzak, T.; Rykoff, E.; Gruen, D.; Armstrong, R.; Bacon, D.; Bechtol, K.; et al

    2015-03-31

    We measure the weak-lensing masses and galaxy distributions of four massive galaxy clusters observed during the Science Verification phase of the Dark Energy Survey. This pathfinder study is meant to 1) validate the DECam imager for the task of measuring weak-lensing shapes, and 2) utilize DECam's large field of view to map out the clusters and their environments over 90 arcmin. We conduct a series of rigorous tests on astrometry, photometry, image quality, PSF modelling, and shear measurement accuracy to single out flaws in the data and also to identify the optimal data processing steps and parameters. We find Sciencemore » Verification data from DECam to be suitable for the lensing analysis described in this paper. The PSF is generally well-behaved, but the modelling is rendered difficult by a flux-dependent PSF width and ellipticity. We employ photometric redshifts to distinguish between foreground and background galaxies, and a red-sequence cluster finder to provide cluster richness estimates and cluster-galaxy distributions. By fitting NFW profiles to the clusters in this study, we determine weak-lensing masses that are in agreement with previous work. For Abell 3261, we provide the first estimates of redshift, weak-lensing mass, and richness. Additionally, the cluster-galaxy distributions indicate the presence of filamentary structures attached to 1E 0657-56 and RXC J2248.7-4431, stretching out as far as 1degree (approximately 20 Mpc), showcasing the potential of DECam and DES for detailed studies of degree-scale features on the sky.« less

  9. Mass and galaxy distributions of four massive galaxy clusters from Dark Energy Survey Science Verification data

    SciTech Connect

    Melchior, P.; et al.

    2015-05-21

    We measure the weak-lensing masses and galaxy distributions of four massive galaxy clusters observed during the Science Verification phase of the Dark Energy Survey. This pathfinder study is meant to 1) validate the DECam imager for the task of measuring weak-lensing shapes, and 2) utilize DECam's large field of view to map out the clusters and their environments over 90 arcmin. We conduct a series of rigorous tests on astrometry, photometry, image quality, PSF modeling, and shear measurement accuracy to single out flaws in the data and also to identify the optimal data processing steps and parameters. We find Science Verification data from DECam to be suitable for the lensing analysis described in this paper. The PSF is generally well-behaved, but the modeling is rendered difficult by a flux-dependent PSF width and ellipticity. We employ photometric redshifts to distinguish between foreground and background galaxies, and a red-sequence cluster finder to provide cluster richness estimates and cluster-galaxy distributions. By fitting NFW profiles to the clusters in this study, we determine weak-lensing masses that are in agreement with previous work. For Abell 3261, we provide the first estimates of redshift, weak-lensing mass, and richness. In addition, the cluster-galaxy distributions indicate the presence of filamentary structures attached to 1E 0657-56 and RXC J2248.7-4431, stretching out as far as 1 degree (approximately 20 Mpc), showcasing the potential of DECam and DES for detailed studies of degree-scale features on the sky.

  10. Mass and galaxy distributions of four massive galaxy clusters from Dark Energy Survey Science Verification data

    SciTech Connect

    Melchior, P.; Suchyta, E.; Huff, E.; Hirsch, M.; Kacprzak, T.; Rykoff, E.; Gruen, D.; Armstrong, R.; Bacon, D.; Bechtol, K.; Bernstein, G. M.; Bridle, S.; Clampitt, J.; Honscheid, K.; Jain, B.; Jouvel, S.; Krause, E.; Lin, H.; MacCrann, N.; Patton, K.; Plazas, A.; Rowe, B.; Vikram, V.; Wilcox, H.; Young, J.; Zuntz, J.; Abbott, T.; Abdalla, F. B.; Allam, S. S.; Banerji, M.; Bernstein, J. P.; Bernstein, R. A.; Bertin, E.; Buckley-Geer, E.; Burke, D. L.; Castander, F. J.; da Costa, L. N.; Cunha, C. E.; Depoy, D. L.; Desai, S.; Diehl, H. T.; Doel, P.; Estrada, J.; Evrard, A. E.; Neto, A. F.; Fernandez, E.; Finley, D. A.; Flaugher, B.; Frieman, J. A.; Gaztanaga, E.; Gerdes, D.; Gruendl, R. A.; Gutierrez, G. R.; Jarvis, M.; Karliner, I.; Kent, S.; Kuehn, K.; Kuropatkin, N.; Lahav, O.; Maia, M. A. G.; Makler, M.; Marriner, J.; Marshall, J. L.; Merritt, K. W.; Miller, C. J.; Miquel, R.; Mohr, J.; Neilsen, E.; Nichol, R. C.; Nord, B. D.; Reil, K.; Roe, N. A.; Roodman, A.; Sako, M.; Sanchez, E.; Santiago, B. X.; Schindler, R.; Schubnell, M.; Sevilla-Noarbe, I.; Sheldon, E.; Smith, C.; Soares-Santos, M.; Swanson, M. E. C.; Sypniewski, A. J.; Tarle, G.; Thaler, J.; Thomas, D.; Tucker, D. L.; Walker, A.; Wechsler, R.; Weller, J.; Wester, W.

    2015-03-31

    We measure the weak-lensing masses and galaxy distributions of four massive galaxy clusters observed during the Science Verification phase of the Dark Energy Survey. This pathfinder study is meant to 1) validate the DECam imager for the task of measuring weak-lensing shapes, and 2) utilize DECam's large field of view to map out the clusters and their environments over 90 arcmin. We conduct a series of rigorous tests on astrometry, photometry, image quality, PSF modelling, and shear measurement accuracy to single out flaws in the data and also to identify the optimal data processing steps and parameters. We find Science Verification data from DECam to be suitable for the lensing analysis described in this paper. The PSF is generally well-behaved, but the modelling is rendered difficult by a flux-dependent PSF width and ellipticity. We employ photometric redshifts to distinguish between foreground and background galaxies, and a red-sequence cluster finder to provide cluster richness estimates and cluster-galaxy distributions. By fitting NFW profiles to the clusters in this study, we determine weak-lensing masses that are in agreement with previous work. For Abell 3261, we provide the first estimates of redshift, weak-lensing mass, and richness. Additionally, the cluster-galaxy distributions indicate the presence of filamentary structures attached to 1E 0657-56 and RXC J2248.7-4431, stretching out as far as 1degree (approximately 20 Mpc), showcasing the potential of DECam and DES for detailed studies of degree-scale features on the sky.

  11. THE SAMI GALAXY SURVEY: TOWARD A UNIFIED DYNAMICAL SCALING RELATION FOR GALAXIES OF ALL TYPES

    SciTech Connect

    Cortese, L.; Glazebrook, K.; Mould, J.; Fogarty, L. M. R.; Bland-Hawthorn, J.; Croom, S. M.; Scott, N.; Allen, J. T.; Bloom, J.; Bryant, J. J.; Ho, I.-T.; Bekki, K.; Colless, M.; Sharp, R.; Couch, W.; Goodwin, M.; Tonini, C.; Cluver, M.; Davies, R. L.; Drinkwater, M. J.; and others

    2014-11-10

    We take advantage of the first data from the Sydney-AAO Multi-object Integral field Galaxy Survey to investigate the relation between the kinematics of gas and stars, and stellar mass in a comprehensive sample of nearby galaxies. We find that all 235 objects in our sample, regardless of their morphology, lie on a tight relation linking stellar mass (M {sub *}) to internal velocity quantified by the S {sub 0.5} parameter, which combines the contribution of both dispersion (σ) and rotational velocity (V {sub rot}) to the dynamical support of a galaxy (S{sub 0.5}=√(0.5 V{sub rot}{sup 2}+σ{sup 2})). Our results are independent of the baryonic component from which σ and V {sub rot} are estimated, as the S {sub 0.5} of stars and gas agree remarkably well. This represents a significant improvement compared to the canonical M {sub *} versus V {sub rot} and M {sub *} versus σ relations. Not only is no sample pruning necessary, but also stellar and gas kinematics can be used simultaneously, as the effect of asymmetric drift is taken into account once V {sub rot} and σ are combined. Our findings illustrate how the combination of dispersion and rotational velocities for both gas and stars can provide us with a single dynamical scaling relation valid for galaxies of all morphologies across at least the stellar mass range 8.5 galaxy kinematics and baryonic content, and a less biased comparison with theoretical models.

  12. The Hawaii K-band galaxy survey. 3: Spectroscopy of K less than 20 galaxies

    NASA Technical Reports Server (NTRS)

    Songaila, A.; Cowie, L. L.; Hu, E. M.; Gardner, J. P.

    1994-01-01

    We present spectra and multicolor (B, I, K) data for near-infrared (K) selected spatially complete magnitude limited (K is less than 20) galaxy samples from the Hawaii Survey. The redshift indentification of the sample of 298 galaxies is substantially complete to a B magnitude of 26 and an I magnitude of 22.5, and identification of observed galaxies ranges from nearly 100% completeness at K is less than 18 to approximately 70% completeness at K = 19-20. We note that many of the unidentified objects appear to be red (I-K) objects which are flat in the optical and spectroscopically featureless. Strengths of spectral-line features and breaks are tabulated for the 262 galaxies with reasonably secure redshifts. The measured redshifts may nearly all fall at z is less than or approximately 1, with the exception of a compact absorption-line object at z = 2.35. At K is less than or equal to 18, the redshift distribution is well fitted by a model with no luminosity evolution, implying that from the K-band Hubble diagram, the Hubble constant can vary at most by 10% over the redshift range from z approximately 0.025 to 0.25, and that positive luminosity evolution at any significant level between z = 0 and z = 1 is ruled out. However, the evolution of both the emission-line strengths and the 4000 A break indicates that galaxies were undergoing significantly more star formation at z = 1 than at the present time.

  13. Enacs Survey of Southern Galaxies Indicates Open Universe

    NASA Astrophysics Data System (ADS)

    1996-02-01

    hundreds, in some cases even thousands of galaxies (each with many billions of stars and much interstellar matter), they also contain hot gas (with a temperature of several million degrees) which is best visible in X-rays, as well as the invisible dark matter just mentioned. In fact, these clusters are the largest and most massive objects that are known today, and a detailed study of their properties can therefore provide insight into the way in which large-scale structures in the Universe have formed. This unique information is encoded into the distribution of the clusters' total masses, of their physical shapes, and not the least in the way they are distributed in space. The need for a `complete' cluster sample Several of these fundamental questions can be studied by observing a few, or at the most several tens of well-chosen clusters. However, if the goal is to discriminate between the various proposed theories of formation of their spatial distribution and thus the Universe's large-scale structure, it is essential that uniform data is collected for a sample of clusters that is complete in a statistical sense. Only then will it be possible to determine reliably the distribution of cluster masses and shapes, etc. For such comprehensive investigations, `complete' samples of clusters (that is, brighter than a certain magnitude and located within a given area in the sky) can be compiled either by means of catalogues like the one published by Abell and his collaborators and based on the distribution of optically selected galaxies, or from large-scale surveys of X-ray sources. However, in both cases, it is of paramount importance to verify the physical reality of the presumed clusters. Sometimes several galaxies are seen in nearly the same direction and therefore appear to form a cluster, but it later turns out that they are at very different distances and do not form a physical entity. This control must be performed through spectroscopic observations of the galaxies in the

  14. Lensing convergence and the neutrino mass scale in galaxy redshift surveys

    NASA Astrophysics Data System (ADS)

    Cardona, Wilmar; Durrer, Ruth; Kunz, Martin; Montanari, Francesco

    2016-08-01

    We demonstrate the importance of including the lensing contribution in galaxy clustering analyses with large galaxy redshift surveys. It is well known that radial cross-correlations between different redshift bins of galaxy surveys are dominated by lensing. But we show here that also neglecting lensing in the autocorrelations within one bin severely biases cosmological parameter estimation with redshift surveys. It leads to significant shifts for several cosmological parameters, most notably the scalar spectral index and the neutrino mass scale. Especially the latter parameter is one of the main targets of future galaxy surveys.

  15. Innovations in adaptive optics imaging and spectroscopy: OSIRIS, galaxy surveys, and galaxy mergers

    NASA Astrophysics Data System (ADS)

    Barczys, Matthew Michael

    This thesis presents the design, construction, and installation of two instruments designed for use with the Keck Telescopes' Adaptive Optics (AO) Systems. It also presents the results of a near-infrared AO survey to measure the pair fraction in faint field galaxies. The instrumentation portion of the thesis concentrates on two main projects, OSIRIS, a near-infrared integral- field spectrograph, and SHARC, a near-infrared camera. OSIRIS is a facility- class instrument at the Keck Observatory, and offers a relatively new spectroscopic capability of simultaneously acquiring infrared spectra ( R ~ 3900) at up to 3000 contiguous locations in an AO-corrected focal plane. SHARC is a camera developed for the Keck AO Team to use with AO-related engineering tasks, including testing and commissioning of the Next-Generation Wavefront Controller. SHARC images a field of up to [Special characters omitted.] on a side, at a spatial resolution of [Special characters omitted.] per pixel throughout the near-infrared (1-2.5 mm). Both instruments were developed in the Infrared Laboratory of the UCLA Department of Physics and Astronomy. The remainder of the thesis describes two near-infrared AO galaxy surveys carried out during the construction of OSIRIS using another instrument partially developed by UCLA. The Keck Observatory Near-Infrared AO Camera (NIRC2) was used to image nearly 700 faint field galaxies (mostly at z ~ 0.5-1.5), with the goal of measuring the near-infrared galaxy pair fraction. This is the first time that AO has been used to measure the pair fraction in field galaxies, and provides a unique opportunity to probe close companions (less than 1 '' ) in the near-infrared. Our measured pair fraction is 0.13 ± 0.04 in both the H - and K ' -bands (1.63mm and 2.12mm) and provides an independent check of optical pair fraction measurements made using the Hubble Space Telescope (HST). While most pairs are observed to have comparable brightness in optical imaging ( dm < 2 mag

  16. Efficient reconstruction of linear baryon acoustic oscillations in galaxy surveys

    NASA Astrophysics Data System (ADS)

    Burden, A.; Percival, W. J.; Manera, M.; Cuesta, Antonio J.; Vargas Magana, Mariana; Ho, Shirley

    2014-12-01

    Reconstructing an estimate of linear baryon acoustic oscillations (BAO) from an evolved galaxy field has become a standard technique in recent analyses. By partially removing non-linear damping caused by bulk motions, the real-space BAO peak in the correlation function is sharpened, and oscillations in the power spectrum are visible to smaller scales. In turn these lead to stronger measurements of the BAO scale. Future surveys are being designed assuming that this improvement has been applied, and this technique is therefore of critical importance for future BAO measurements. A number of reconstruction techniques are available, but the most widely used is a simple algorithm that decorrelates large-scale and small-scale modes approximately removing the bulk-flow displacements by moving the overdensity field. We consider the practical implementation of this algorithm, looking at the efficiency of reconstruction as a function of the assumptions made for the bulk-flow scale, the shot-noise level in a random catalogue used to quantify the mask and the method used to estimate the bulk-flow shifts. We also examine the efficiency of reconstruction against external factors including galaxy density, volume and edge effects, and consider their impact for future surveys. Throughout we make use of the mocks catalogues created for the Baryon Oscillation Spectroscopic Survey (BOSS) Date Release 11 samples covering 0.43 < z < 0.7 (CMASS) and 0.15 < z < 0.43 (LOWZ), to empirically test these changes.

  17. IMPROVED MOCK GALAXY CATALOGS FOR THE DEEP2 GALAXY REDSHIFT SURVEY FROM SUBHALO ABUNDANCE AND ENVIRONMENT MATCHING

    SciTech Connect

    Gerke, Brian F.; Wechsler, Risa H.; Behroozi, Peter S.; Yan, Renbin; Coil, Alison L.

    2013-09-15

    We develop empirical methods for modeling the galaxy population and populating cosmological N-body simulations with mock galaxies according to the observed properties of galaxies in survey data. We use these techniques to produce a new set of mock catalogs for the DEEP2 Galaxy Redshift Survey based on the output of the high-resolution Bolshoi simulation, as well as two other simulations with different cosmological parameters, all of which we release for public use. The mock-catalog creation technique uses subhalo abundance matching to assign galaxy luminosities to simulated dark-matter halos. It then adds color information to the resulting mock galaxies in a manner that depends on the local galaxy density, in order to reproduce the measured color-environment relation in the data. In the course of constructing the catalogs, we test various models for including scatter in the relation between halo mass and galaxy luminosity, within the abundance-matching framework. We find that there is no constant-scatter model that can simultaneously reproduce both the luminosity function and the autocorrelation function of DEEP2. This result has implications for galaxy-formation theory, and it restricts the range of contexts in which the mock catalogs can be usefully applied. Nevertheless, careful comparisons show that our new mock catalogs accurately reproduce a wide range of the other properties of the DEEP2 catalog, suggesting that they can be used to gain a detailed understanding of various selection effects in DEEP2.

  18. Loose Groups of Galaxies in the Las Campanas Redshift Survey

    NASA Astrophysics Data System (ADS)

    Tucker, Douglas L.; Oemler, Augustus, Jr.; Hashimoto, Yasuhiro; Shectman, Stephen A.; Kirshner, Robert P.; Lin, Huan; Landy, Stephen D.; Schechter, Paul L.; Allam, Sahar S.

    2000-10-01

    A ``friends-of-friends'' percolation algorithm has been used to extract a catalog of δn/n=80 density enhancements (groups) from the six slices of the Las Campanas Redshift Survey (LCRS). The full catalog contains 1495 groups and includes 35% of the LCRS galaxy sample. A clean sample of 394 groups has been derived by culling groups from the full sample that either are too close to a slice edge, have a crossing time greater than a Hubble time, have a corrected velocity dispersion of zero, or contain a 55" ``orphan'' (a galaxy with a mock redshift that was excluded from the original LCRS redshift catalog due to its proximity to another galaxy-i.e., within 55"). Median properties derived from the clean sample include a line-of-sight velocity dispersion σlos=164 km s-1, crossing time tcr=0.10 H-10, harmonic radius Rh=0.58 h-1 Mpc, pairwise separation Rp=0.64 h-1 Mpc, virial mass Mvir=1.90×1013 h-1 Msolar, total group R-band luminosity Ltot=1.30×1011 h-2 Lsolar, and R-band mass-to-light ratio M/L=171 h Msolar/Lsolar the median number of observed members in a group is three.

  19. Loose groups of galaxies in the Perseus-Pisces survey

    NASA Astrophysics Data System (ADS)

    Trasarti-Battistoni, R.

    1998-06-01

    We present a large catalog of loose groups of galaxies in the Southern Galactic Hemisphere, selected from the Perseus-Pisces redshift Survey (PPS). Particular care is taken in order to obtain group samples as homogeneous as possible to previously published catalogs. All our catalogs contain about 200 groups, significantly more than in most previous studies where group samples were obtained from galaxy data sets of comparable quality to (but smaller extent than) PPS. Groups are identified with the adaptive Friends-Of-Friends (FOF) algorithm of \\cite[Huchra & Geller (1982),]{HG82} with suitable normalizations D_0=0.231 \\ h(-1) Mpc and V_0=350 \\ km \\ s(-1) at cz_0=1000 \\ km \\ s(-1) . The luminosity function (LF) normalization phi_ *=0.02 \\ h(3) \\ Mpc(-3) appropriate for PPS yields a number density threshold delta n/n ~ 180 for the adopted D_0, instead of delta n/n ~ 80 used in previous studies of other samples. However, the customary choice of D_0 obtained (through the LF) from a fixed mass overdensity delta rho / rho =80, well motivated in theory, suffers from important observational uncertainties and sample-to-sample variations of the LF normalization, and from major uncertainties in the relation between galaxy density n and mass density rho . We discuss how to self-consistently match FOF parameters among different galaxy samples. We then separately vary several FOF and sample parameters, and discuss their effect on group properties. Loose groups in PPS nicely trace the large scale structure (LSS) in the parent galaxy sample. The group properties vary little with different redshift corrections, redshift cut-off, and galaxy LF, but are rather sensitive to the adopted links D_0 and V_0. More precisely, the typical group size (velocity dispersion) is linearly related to the adopted distance (velocity) link, while it is rather insensitive to the adopted velocity (distance) link. Physical properties of groups in PPS and in directly comparable samples show good

  20. A survey of HI gas toward the Andromeda galaxy

    NASA Astrophysics Data System (ADS)

    Kerp, J.; Kalberla, P. M. W.; Ben Bekhti, N.; Flöer, L.; Lenz, D.; Winkel, B.

    2016-05-01

    Context. The subsequent coalescence of low-mass halos over cosmic time is thought to be the major formation channel of massive spiral galaxies like the Milky Way and the Andromeda galaxy (M 31). The gaseous halo of a massive galaxy is considered to be the reservoir of baryonic matter persistently fueling the star formation in the disk. Because of its proximity, M 31 is the ideal object for studying the structure of the halo gas in great detail. Aims: Using the latest neutral atomic hydrogen (HI) data of the Effelsberg-Bonn HI Survey (EBHIS) allows comprising a comprehensive inventory of gas associated with M 31. The primary aim is to differentiate between physical structures belonging to the Milky Way Galaxy and M 31 and accordingly to test the presence of a M 31 neutral gaseous halo. Methods: Analyzing the spatially fully sampled EBHIS data makes it feasible to trace coherent HI structures in space and radial velocity. To disentangle Milky Way and M 31 HI emission we use a new approach, along with the traditional path of setting an upper radial velocity limit, by calculating a difference second moment map. Results: We argue that M 31's disk is physically connected to an asymmetric HI halo of tens of kpc size, the M 31 cloud. We confirm the presence of a coherent low-velocity HI filament located in between M 31 and M 33 aligned at the sky with the clouds at systemic velocity. The physical parameters of the HI filament are comparable to those of the HI clouds at systemic velocity. We also detected an irregularly shaped HI cloud that is is positionally located close to but offset from the stellar body of And XIX.

  1. A faint galaxy redshift survey behind massive clusters

    SciTech Connect

    Frye, Brenda

    1999-12-01

    This thesis is concerned with the gravitational lensing effect by massive galaxy clusters. We have explored a new technique for measuring galaxy masses and for detecting high-z galaxies by their optical colors. A redshift survey has been obtained at the Keck for a magnitude limited sample of objects (I<23) behind three clusters, A1689, A2390, and A2218 within a radius of 0.5M pc. For each cluster we see both a clear trend of increasing flux and redshift towards the center. This behavior is the result of image magnifications, such that at fixed redshift one sees further down the luminosity function. The gradient of this magnification is, unlike measurements of image distortion, sensitive to the mass profile, and found to depart strongly from a pure isothermal halo. We have found that V RI color selection can be used effectively as a discriminant for finding high-z galaxies behind clusters and present five 4.1 < z < 5.1 spectra which are of very high quality due to their high mean magnification of {approximately}20, showing strong, visibly-saturated interstellar metal lines in some cases. We have also investigated the radio ring lens PKS 1830-211, locating the source and multiple images and detected molecular absorption at mm wavelengths. Broad molecular absorption of width 1/40kms is found toward the southwest component only, where surprisingly it does not reach the base of the continuum, which implies incomplete coverage of the SW component by molecular gas, despite the small projected size of the source, less than 1/8h pc at the absorption redshift.

  2. Spitzer Survey of the Large Magellanic Cloud: Surveying the Agents of a Galaxy's Evolution (SAGE)

    NASA Astrophysics Data System (ADS)

    Meixner, Margaret; Babler, Brian; Bernard, Jean-Philippe; Blum, Robert; Boulanger, Francois; Churchwell, Edward; Cohen, Martin; Engelbracht, Charles; Frogel, Jay; Fukui, Yasuo; Gallagher, Jay; Gordon, Karl; Gorjian, Varoujan; Harris, Jason; Hora, Joseph; Indebetouw, Remy; Jansen, Stephen; Kawamura, Akiko; Kelly, Douglas; Kemper, Ciska; Latter, William; Leitherer, Claus; Madden, Suzanne; Meade, Marilyn; Misselt, Karl; Mizuno, Norikazu; Mizuno, Akira; Mould, Jeremy; Nota, Antonella; Oey, Sally; Olsen, Knut; Onishi, Toshikazu; Paladini, Roberta; Panagia, Nino; Perez-Gonzalez, Pablo; Reach, William; Shibai, Hiroshi; Shuji, Sato; Smith, Linda; Staveley-Smith, Lister; Tielens, Xander; Ueta, Toshiya; van Dyk, Schuyler; Volk, Kevin; Werner, Michael; Whitney, Barbara; Zaritsky, Dennis

    2005-06-01

    The recycling of matter between the interstellar medium (ISM) and stars drives the evolution of a galaxy's visible matter. To understand this recycling, we propose to study the physical processes of the ISM, the formation of new stars and the injection of mass by evolved stars and their relationships on the galaxy-wide scale of the Large Magellanic Cloud (LMC). Due to its proximity, favorable viewing angle, multi-wavelength information, and measured tidal interactions with the Milky Way (MW) and Small Magellanic Cloud (SMC), the LMC is uniquely suited for surveying the agents of a galaxy's evolution (SAGE), the ISM and stars. Our uniform and unbiased survey of the LMC (7x7 degrees) in all IRAC and MIPS bands will have much better wavelength coverage, up to ~1000 times better point source sensitivity and ~11 times better angular resolution than previous IR surveys. Full and uniform coverage of the LMC is necessary to study the galaxy as a system, to develop a template for more distant galaxies and to create an archival data set (rights waived) that promises a lasting legacy to match current LMC surveys at other wavelengths. SAGE will reveal over 6 million sources including ~150,000 evolved stars, ~50,000 young stellar objects and the diffuse ISM with column densities >1.2e21 H/cm2. In contrast to the MW and SMC, the diffuse IR emission in the LMC can be unambiguously associated with individual gas/dust clouds, thereby permitting unique studies of dust processes in the ISM. SAGE's complete census of newly formed stars with masses >1-3 Msun will reveal whether tidally-triggered star formation events in the LMC are sustained or short-lived. SAGE's complete census of evolved stars with mass loss rates >1e-8 Msun/yr will quantitatively measure the rate at which evolved stars inject mass into the ISM. SAGE will be the crucial link between Spitzer's survey of individual IR sources in the MW (GLIMPSE) and its surveys of galaxies (e.g., SINGS) and a stepping stone to the

  3. Distant Compact Clusters of Galaxies from the BMW survey

    NASA Astrophysics Data System (ADS)

    Dell'Antonio, Ian; Guzzo, Luigi; Longhetti, Marcella; Moretti, Alberto; Campana, Sergio; Lazzati, Davide; Panzera, Mariarosa; Tagliaferri, Gianpiero

    2002-02-01

    We propose to use SQIID to identify high-redshift clusters of galaxies from the BMW, an X-ray selected sample of serendipitously detected extended sources from the ROSAT HRI archive. The BMW survey is unique because of the superior angular resolution of the HRI. In fact, this is the only modern sample of distant clusters available that is not based on the low-resolution PSPC. Using 4m optical imaging, we have already identified several high-redshift clusters, two of which have z> 0.8, thus confirming the ability of the survey to peer efficiently into the z~ 1 regime, where only a handful of X-ray clusters are known. To test the evolution of the cluster abundance, we must increase the number of clusters known in this redshift regime. The BMW survey provides us with the only current opportunity to study compact clusters missing in all PSPC surveys. Because z~ 1 ellipticals have very red colors, K-band imaging is the most effective way of identifying these clusters. With SQIID, we also can obtain redshift estimates via the J-K red sequence. We propose near-IR imaging in J,H,K of 30 highest-z cluster candidates from the BMW survey, as indicated by their small size and low flux. This will allow efficient use of 8-meter spectroscopy to follow up the high-end tail of the redshift distribution.

  4. Photometric identification of objects from Galaxy Evolution Explorer Survey and Sloan Digital Sky Survey

    NASA Astrophysics Data System (ADS)

    Preethi, K.; Gudennavar, S. B.; Bubbly, S. G.; Murthy, Jayant; Brosch, Noah

    2014-01-01

    We have used Galaxy Evolution Explorer (GALEX) and Sloan Digital Sky Survey (SDSS) observations to extract seven band photometric magnitudes for over 80 000 objects in the vicinity of the North Galactic Pole. Although these had been identified as stars by the SDSS pipeline, we found through fitting with model spectral energy distributions that most were, in fact, of extragalactic origin. Only about 9 per cent of these objects turned out to be main-sequence stars and about 11 per cent were white dwarfs and red giants collectively, while galaxies and quasars contributed to the remaining 80 per cent of the data. We have classified these objects into different spectral types (for the stars) and into different galactic types (for the galaxies). As part of our fitting procedure, we derive the distance and extinction to each object and the photometric redshift towards galaxies and quasars. This method easily allows for the addition of any number of observations to cover a more diverse range of wavelengths, as well as the addition of any number of model templates. The primary objective of this work is to eventually derive a three-dimensional extinction map of the Milky Way Galaxy.

  5. Hα Emitting Galaxies in the Deep And Wide Narrowband Survey

    NASA Astrophysics Data System (ADS)

    Gonzalez, Alicia; Malhotra, Sangeeta; Rhoads, James E.; DAWN Collaboration

    2016-06-01

    We present new measurements of the Hα luminosity function (LF) and star formation rate (SFR) volume density for galaxies at z˜0.62. Our results are part of the Deep And Wide Narrowband Survey (DAWN), a unique infrared imaging program with large areal coverage (˜1.1 deg2 over 5 fields) and sensitivity (9.9 × 10-18 erg/cm2/s at 5σ). The present sample, based on a single DAWN field, contains 85 Hα emission-line candidates at z˜0.62, 25% of which have spectroscopic confirmations. These candidates have been selected through comparison of narrow and broad-band images and through matching with existing catalogs in the COSMOS field. The dust-corrected LF is well described by a Schechter function. We calculate a SFR density of ρSFR =10(-1.15±0.07) M○ / yr/ Mpc3. We compare our results to already existing surveys at similar redshifts and find that our faint slope of the LF is flatter than that of most other surveys and that our SFR density is higher than that reported from similar surveys at z<2.

  6. The Wide-Field Nearby Galaxy-Cluster Survey (WINGS) and Its Extension OMEGAWINGS

    NASA Astrophysics Data System (ADS)

    Poggianti, B. M.; Fasano, G.; Bettoni, D.; Cava, A.; Couch, W.; D'Onofrio, M.; Dressler, A.; Fritz, J.; Kjaergaard, P.; Gullieuszik, M.; Moles, M.; Moretti, A.; Omizzolo, A.; Paccagnella, A.; Varela, J.; Vulcani, B.

    WINGS is a wide-field multi-wavelength survey of 76 X-ray selected clusters at low redshift. The WINGS database has been used for a variety of cluster and cluster galaxy studies, investigating galaxy star formation, morphologies, structure, stellar mass functions and other properties. We present the recent wider-field extension of WINGS, OMEGAWINGS, conducted with OmegaCAM@VST and AAOmega@AAT. We show two of our latest results regarding jellyfish galaxies and galaxy sizes. OMEGAWINGS has allowed the first systematic search of galaxies with signs of ongoing ram pressure stripping (jellyfishes), yielding a catalog of ˜ 240 galaxies in 41 clusters. We discuss the first results obtained from this sample and the prospects for integral field data. Finally, we summarize our results regarding the discovery of compact massive galaxies at low redshift, their properties, dependence on environment and the implications for the evolution of galaxy sizes from high- to low-z.

  7. Shocked POststarbust Galaxy Survey. I. Candidate Post-starbust Galaxies with Emission Line Ratios Consistent with Shocks

    NASA Astrophysics Data System (ADS)

    Alatalo, Katherine; Cales, Sabrina L.; Rich, Jeffrey A.; Appleton, Philip N.; Kewley, Lisa J.; Lacy, Mark; Lanz, Lauranne; Medling, Anne M.; Nyland, Kristina

    2016-06-01

    There are many mechanisms by which galaxies can transform from blue, star-forming spirals, to red, quiescent early-type galaxies, but our current census of them does not form a complete picture. Recent observations of nearby case studies have identified a population of galaxies that quench “quietly.” Traditional poststarburst searches seem to catch galaxies only after they have quenched and transformed, and thus miss any objects with additional ionization mechanisms exciting the remaining gas. The Shocked POststarburst Galaxy Survey (SPOGS) aims to identify transforming galaxies, in which the nebular lines are excited via shocks instead of through star formation processes. Utilizing the Oh-Sarzi-Schawinski-Yi (OSSY) measurements on the Sloan Digital Sky Survey Data Release 7 catalog, we applied Balmer absorption and shock boundary criteria to identify 1067 SPOG candidates (SPOGs*) within z = 0.2. SPOGs* represent 0.2% of the OSSY sample galaxies that exceed the continuum signal-to-noise cut (and 0.7% of the emission line galaxy sample). SPOGs* colors suggest that they are in an earlier phase of transition than OSSY galaxies that meet an “E+A” selection. SPOGs* have a 13% 1.4 GHz detection rate from the Faint Images of the Radio Sky at Twenty Centimeters Survey, higher than most other subsamples, and comparable only to low-ionization nuclear emission line region hosts, suggestive of the presence of active galactic nuclei (AGNs). SPOGs* also have stronger Na i D absorption than predicted from the stellar population, suggestive of cool gas being driven out in galactic winds. It appears that SPOGs* represent an earlier phase in galaxy transformation than traditionally selected poststarburst galaxies, and that a large proportion of SPOGs* also have properties consistent with disruption of their interstellar media, a key component to galaxy transformation. It is likely that many of the known pathways to transformation undergo a SPOG phase. Studying this sample of

  8. Galaxy bias from the Dark Energy Survey Science Verification data: Combining galaxy density maps and weak lensing maps

    DOE PAGES

    Chang, C.; Pujol, A.; Gaztañaga, E.; Amara, A.; Réfrégier, A.; Bacon, D.; Becker, M. R.; Bonnett, C.; Carretero, J.; Castander, F. J.; et al

    2016-04-15

    We measure the redshift evolution of galaxy bias for a magnitude-limited galaxy sample by combining the galaxy density maps and weak lensing shear maps for a ~116 deg2 area of the Dark Energy Survey (DES) Science Verification (SV) data. This method was first developed in Amara et al. and later re-examined in a companion paper with rigorous simulation tests and analytical treatment of tomographic measurements. In this work we apply this method to the DES SV data and measure the galaxy bias for a i < 22.5 galaxy sample. We find the galaxy bias and 1σ error bars in fourmore » photometric redshift bins to be 1.12 ± 0.19 (z = 0.2–0.4), 0.97 ± 0.15 (z = 0.4–0.6), 1.38 ± 0.39 (z = 0.6–0.8), and 1.45 ± 0.56 (z = 0.8–1.0). These measurements are consistent at the 2σ level with measurements on the same data set using galaxy clustering and cross-correlation of galaxies with cosmic microwave background lensing, with most of the redshift bins consistent within the 1σ error bars. In addition, our method provides the only σ8 independent constraint among the three. We forward model the main observational effects using mock galaxy catalogues by including shape noise, photo-z errors, and masking effects. We show that our bias measurement from the data is consistent with that expected from simulations. With the forthcoming full DES data set, we expect this method to provide additional constraints on the galaxy bias measurement from more traditional methods. Moreover, in the process of our measurement, we build up a 3D mass map that allows further exploration of the dark matter distribution and its relation to galaxy evolution.« less

  9. Galaxy bias from the Dark Energy Survey Science Verification data: combining galaxy density maps and weak lensing maps

    NASA Astrophysics Data System (ADS)

    Chang, C.; Pujol, A.; Gaztañaga, E.; Amara, A.; Réfrégier, A.; Bacon, D.; Becker, M. R.; Bonnett, C.; Carretero, J.; Castander, F. J.; Crocce, M.; Fosalba, P.; Giannantonio, T.; Hartley, W.; Jarvis, M.; Kacprzak, T.; Ross, A. J.; Sheldon, E.; Troxel, M. A.; Vikram, V.; Zuntz, J.; Abbott, T. M. C.; Abdalla, F. B.; Allam, S.; Annis, J.; Benoit-Lévy, A.; Bertin, E.; Brooks, D.; Buckley-Geer, E.; Burke, D. L.; Capozzi, D.; Rosell, A. Carnero; Kind, M. Carrasco; Cunha, C. E.; D'Andrea, C. B.; da Costa, L. N.; Desai, S.; Diehl, H. T.; Dietrich, J. P.; Doel, P.; Eifler, T. F.; Estrada, J.; Evrard, A. E.; Flaugher, B.; Frieman, J.; Goldstein, D. A.; Gruen, D.; Gruendl, R. A.; Gutierrez, G.; Honscheid, K.; Jain, B.; James, D. J.; Kuehn, K.; Kuropatkin, N.; Lahav, O.; Li, T. S.; Lima, M.; Marshall, J. L.; Martini, P.; Melchior, P.; Miller, C. J.; Miquel, R.; Mohr, J. J.; Nichol, R. C.; Nord, B.; Ogando, R.; Plazas, A. A.; Reil, K.; Romer, A. K.; Roodman, A.; Rykoff, E. S.; Sanchez, E.; Scarpine, V.; Schubnell, M.; Sevilla-Noarbe, I.; Smith, R. C.; Soares-Santos, M.; Sobreira, F.; Suchyta, E.; Swanson, M. E. C.; Tarle, G.; Thomas, D.; Walker, A. R.

    2016-07-01

    We measure the redshift evolution of galaxy bias for a magnitude-limited galaxy sample by combining the galaxy density maps and weak lensing shear maps for a ˜116 deg2 area of the Dark Energy Survey (DES) Science Verification (SV) data. This method was first developed in Amara et al. and later re-examined in a companion paper with rigorous simulation tests and analytical treatment of tomographic measurements. In this work we apply this method to the DES SV data and measure the galaxy bias for a i < 22.5 galaxy sample. We find the galaxy bias and 1σ error bars in four photometric redshift bins to be 1.12 ± 0.19 (z = 0.2-0.4), 0.97 ± 0.15 (z = 0.4-0.6), 1.38 ± 0.39 (z = 0.6-0.8), and 1.45 ± 0.56 (z = 0.8-1.0). These measurements are consistent at the 2σ level with measurements on the same data set using galaxy clustering and cross-correlation of galaxies with cosmic microwave background lensing, with most of the redshift bins consistent within the 1σ error bars. In addition, our method provides the only σ8 independent constraint among the three. We forward model the main observational effects using mock galaxy catalogues by including shape noise, photo-z errors, and masking effects. We show that our bias measurement from the data is consistent with that expected from simulations. With the forthcoming full DES data set, we expect this method to provide additional constraints on the galaxy bias measurement from more traditional methods. Furthermore, in the process of our measurement, we build up a 3D mass map that allows further exploration of the dark matter distribution and its relation to galaxy evolution.

  10. THE SINS/zC-SINF SURVEY OF z {approx} 2GALAXY KINEMATICS: THE NATURE OF DISPERSION-DOMINATED GALAXIES

    SciTech Connect

    Newman, Sarah F.; Genzel, Reinhard; Foerster Schreiber, Natascha M.; Buschkamp, Peter; Davies, Ric; Eisenhauer, Frank; Kurk, Jaron; Lutz, Dieter; Shapiro Griffin, Kristen; Mancini, Chiara; Renzini, Alvio; Lilly, Simon J.; Carollo, C. Marcella; Peng, Yingjie; Bouche, Nicolas; Burkert, Andreas; Cresci, Giovanni; Genel, Shy; Hicks, Erin K. S.; Naab, Thorsten; and others

    2013-04-20

    We analyze the spectra, spatial distributions, and kinematics of H{alpha}, [N II], and [S II] emission in a sample of 38, z {approx} 2.2 UV/optically selected star-forming galaxies (SFGs) from the SINS and zC-SINF surveys, 34 of which were observed in the adaptive optics mode of SINFONI and 30 of those contain data presented for the first time here. This is supplemented by kinematic data from 43 z {approx} 1-2.5 galaxies from the literature. None of these 81 galaxies is an obvious major merger. We find that the kinematic classification of high-z SFGs as ''dispersion dominated'' or ''rotation dominated'' correlates most strongly with their intrinsic sizes. Smaller galaxies are more likely ''dispersion-dominated'' for two main reasons: (1) the rotation velocity scales linearly with galaxy size but intrinsic velocity dispersion does not depend on size or may even increase in smaller galaxies, and as such, their ratio is systematically lower for smaller galaxies, and (2) beam smearing strongly decreases large-scale velocity gradients and increases observed dispersion much more for galaxies with sizes at or below the resolution. Dispersion-dominated SFGs may thus have intrinsic properties similar to ''rotation-dominated'' SFGs, but are primarily more compact, lower mass, less metal enriched, and may have higher gas fractions, plausibly because they represent an earlier evolutionary state.

  11. Next generation cosmology: constraints from the Euclid galaxy cluster survey

    NASA Astrophysics Data System (ADS)

    Sartoris, B.; Biviano, A.; Fedeli, C.; Bartlett, J. G.; Borgani, S.; Costanzi, M.; Giocoli, C.; Moscardini, L.; Weller, J.; Ascaso, B.; Bardelli, S.; Maurogordato, S.; Viana, P. T. P.

    2016-06-01

    We study the characteristics of the galaxy cluster samples expected from the European Space Agency's Euclid satellite and forecast constraints on parameters describing a variety of cosmological models. In this paper we use the same method of analysis already adopted in the Euclid Red Book, which is based on the Fisher matrix approach. Based on our analytical estimate of the cluster selection function in the photometric Euclid survey, we forecast the constraints on cosmological parameters corresponding to different extensions of the standard Λ cold dark matter model. Using only Euclid clusters, we find that the amplitude of the matter power spectrum will be constrained to Δσ8 = 0.0014 and the mass density parameter to ΔΩm = 0.0011. The dynamical evolution of dark energy will be constrained to Δw0 = 0.03 and Δwa = 0.2 with free curvature Ωk, resulting in a (w0, wa) figure of merit (FoM) of 291. In combination with Planck cosmic microwave background (CMB) constraints, the amplitude of primordial non-Gaussianity will be constrained to ΔfNL ≃ 6.6 for the local shape scenario. The growth factor parameter γ, which signals deviations from general relativity, will be constrained to Δγ = 0.02, and the neutrino density parameter to ΔΩν = 0.0013 (or Δ∑mν = 0.01). Including the Planck CMB covariance matrix improves dark energy constraints to Δw0 = 0.02, Δwa = 0.07, and a FoM = 802. Knowledge of the observable-cluster mass scaling relation is crucial to reach these accuracies. Imaging and spectroscopic capabilities of Euclid will enable internal mass calibration from weak lensing and the dynamics of cluster galaxies, supported by external cluster surveys.

  12. CS (5-4) survey towards nearby infrared bright galaxies

    NASA Astrophysics Data System (ADS)

    Wang, Junzhi; Zhang, Zhiyu; Shi, Yong

    2011-09-01

    With the observations of the CS (5-4) line towards a sample of 24 infrared bright galaxies using Heinrich Hertz Submillimeter Telescope (HHSMT), we detected CS (5-4) emission in 14 galaxies, including 12 ultraluminous infrared galaxies (ULIRGs)/luminous infrared galaxies (LIRGs) and two nearby normal galaxies. As a good dense gas tracer, which has been well used for studying star formation in the Milky Way, CS (5-4) can trace the active star-forming gas in galaxies. The correlation between CS (5-4) luminosity, which is estimated with detected CS (5-4) line emission, and the infrared luminosity in these 14 galaxies, is fitted with a correlation coefficient of 0.939 and a slope close to unity. This correlation confirms that dense gas, which is closely linked to star formation, is very important for understanding star formation in galaxies.

  13. The SAGES Legacy Unifying Globulars and GalaxieS Survey (SLUGGS): Sample Definition, Methods, and Initial Results

    NASA Astrophysics Data System (ADS)

    Brodie, Jean P.; Romanowsky, Aaron J.; Strader, Jay; Forbes, Duncan A.; Foster, Caroline; Jennings, Zachary G.; Pastorello, Nicola; Pota, Vincenzo; Usher, Christopher; Blom, Christina; Kader, Justin; Roediger, Joel C.; Spitler, Lee R.; Villaume, Alexa; Arnold, Jacob A.; Kartha, Sreeja S.; Woodley, Kristin A.

    2014-11-01

    We introduce and provide the scientific motivation for a wide-field photometric and spectroscopic chemodynamical survey of nearby early-type galaxies (ETGs) and their globular cluster (GC) systems. The SAGES Legacy Unifying Globulars and GalaxieS (SLUGGS) survey is being carried out primarily with Subaru/Suprime-Cam and Keck/DEIMOS. The former provides deep gri imaging over a 900 arcmin2 field-of-view to characterize GC and host galaxy colors and spatial distributions, and to identify spectroscopic targets. The NIR Ca II triplet provides GC line-of-sight velocities and metallicities out to typically ~8 R e, and to ~15 R e in some cases. New techniques to extract integrated stellar kinematics and metallicities to large radii (~2-3 R e) are used in concert with GC data to create two-dimensional (2D) velocity and metallicity maps for comparison with simulations of galaxy formation. The advantages of SLUGGS compared with other, complementary, 2D-chemodynamical surveys are its superior velocity resolution, radial extent, and multiple halo tracers. We describe the sample of 25 nearby ETGs, the selection criteria for galaxies and GCs, the observing strategies, the data reduction techniques, and modeling methods. The survey observations are nearly complete and more than 30 papers have so far been published using SLUGGS data. Here we summarize some initial results, including signatures of two-phase galaxy assembly, evidence for GC metallicity bimodality, and a novel framework for the formation of extended star clusters and ultracompact dwarfs. An integrated overview of current chemodynamical constraints on GC systems points to separate, in situ formation modes at high redshifts for metal-poor and metal-rich GCs.

  14. Using Data Mining to Find Bent-Double Radio Galaxies in the FIRST Survey

    SciTech Connect

    Kamath,C; Cantu-Paz,E; Fodor,I; Tang,N A

    2001-06-22

    In this paper, the authors describe the use of data mining techniques to search for radio-emitting galaxies with a bent-double morphology. In the past, astronomers from the FIRST (Faint Images of the Radio Sky at Twenty-cm) survey identified these galaxies through visual inspection. This was not only subjective but also tedious as the on-going survey now covers 8000 square degrees, with each square degree containing about 90 galaxies. In this paper, they describe how data mining can be used to automate the identification of these galaxies. They discuss the challenges faced in defining meaningful features that represent the shape of a galaxy and their experiences with ensembles of decision trees for the classification of bent-double galaxies.

  15. A sample of galaxy pairs identified from the LAMOST spectral survey and the Sloan Digital Sky Survey

    NASA Astrophysics Data System (ADS)

    Shen, Shi-Yin; Argudo-Fernández, Maria; Chen, Li; Chen, Xiao-Yan; Feng, Shuai; Hou, Jin-Liang; Hou, Yong-Hui; Jiang, Peng; Jing, Yi-Peng; Kong, Xu; Luo, A.-Li; Luo, Zhi-Jian; Shao, Zheng-Yi; Wang, Ting-Gui; Wang, Wen-Ting; Wang, Yue-Fei; Wu, Hong; Wu, Xue-Bing; Yang, Hai-Feng; Yang, Ming; Yuan, Fang-Ting; Yuan, Hai-Long; Zhang, Hao-Tong; Zhang, Jian-Nan; Zhang, Yong

    2016-03-01

    A small fraction (< 10%) of the SDSS main galaxy (MG) sample has not been targeted with spectroscopy due to the effect of fiber collisions. These galaxies have been compiled into the input catalog of the LAMOST ExtraGAlactic Surveys and named the complementary galaxy sample. In this paper, we introduce this project and status of the spectroscopies associated with the complementary galaxies in the first two years of the LAMOST spectral survey (till Sep. of 2014). Moreover, we present a sample of 1102 galaxy pairs identified from the LAMOST complementary galaxies and SDSS MGs, which are defined as two members that have a projected distance smaller than 100 h‑170kpc and a recessional velocity difference smaller than 500 km s‑1. Compared with galaxy pairs that are only selected from SDSS, the LAMOST-SDSS pairs have the advantages of not being biased toward large separations and therefore act as a useful supplement in statistical studies of galaxy interaction and galaxy merging.

  16. Host galaxy spectra and consequences for supernova typing from the SDSS SN survey

    SciTech Connect

    Olmstead, Matthew D.; Brown, Peter J.; Brownstein, Joel R.; Dawson, Kyle S.; Sako, Masao; Gupta, Ravi R.; Bassett, Bruce; Kunz, Martin; Bizyaev, Dmitry; Brinkmann, J.; Brewington, Howard; Ebelke, Garrett L.; Campbell, Heather; D'Andrea, Chris B.; Lampeitl, Hubert; Frieman, Joshua A.; Galbany, Lluís; Garnavich, Peter; Hlozek, Renee; Jha, Saurabh W.; and others

    2014-04-01

    We present the spectroscopy from 5254 galaxies that hosted supernovae (SNe) or other transient events in the Sloan Digital Sky Survey II (SDSS-II). Obtained during SDSS-I, SDSS-II, and the Baryon Oscillation Spectroscopic Survey, this sample represents the largest systematic, unbiased, magnitude limited spectroscopic survey of SN host galaxies. Using the host galaxy redshifts, we test the impact of photometric SN classification based on SDSS imaging data with and without using spectroscopic redshifts of the host galaxies. Following our suggested scheme, there are a total of 1166 photometrically classified SNe Ia when using a flat redshift prior and 1126 SNe Ia when the host spectroscopic redshift is assumed. For 1024 (87.8%) candidates classified as likely SNe Ia without redshift information, we find that the classification is unchanged when adding the host galaxy redshift. Using photometry from SDSS imaging data and the host galaxy spectra, we also report host galaxy properties for use in future analysis of SN astrophysics. Finally, we investigate the differences in the interpretation of the light curve properties with and without knowledge of the redshift. Without host galaxy redshifts, we find that SALT2 light curve fits are systematically biased toward lower photometric redshift estimates and redder colors in the limit of low signal-to-noise data. The general improvements in performance of the light curve fitter and the increased diversity of the host galaxy sample highlights the importance of host galaxy spectroscopy for current photometric SN surveys such as the Dark Energy Survey and future surveys such as the Large Synoptic Survey Telescope.

  17. The signature of dark energy perturbations in galaxy cluster surveys

    SciTech Connect

    Abramo, L.R.; Batista, R.C.; Rosenfeld, R. E-mail: rbatista@fma.if.usp.br

    2009-07-01

    Models of dynamical dark energy unavoidably possess fluctuations in the energy density and pressure of that new component. In this paper we estimate the impact of dark energy fluctuations on the number of galaxy clusters in the Universe using a generalization of the spherical collapse model and the Press-Schechter formalism. The observations we consider are several hypothetical Sunyaev-Zel'dovich and weak lensing (shear maps) cluster surveys, with limiting masses similar to ongoing (SPT, DES) as well as future (LSST, Euclid) surveys. Our statistical analysis is performed in a 7-dimensional cosmological parameter space using the Fisher matrix method. We find that, in some scenarios, the impact of these fluctuations is large enough that their effect could already be detected by existing instruments such as the South Pole Telescope, when priors from other standard cosmological probes are included. We also show how dark energy fluctuations can be a nuisance for constraining cosmological parameters with cluster counts, and point to a degeneracy between the parameter that describes dark energy pressure on small scales (the effective sound speed) and the parameters describing its equation of state.

  18. KPNO 0.9m H(alpha) Imaging Survey of ``Transforming Galaxies" in Local Galaxy Groups

    NASA Astrophysics Data System (ADS)

    Haines, Christopher; O'Sullivan, Ewan; Raychaudhury, Somak; Gargiulo, Adriana; Campusano, Luis

    2012-02-01

    We propose to use the KPNO 0.9-m telescope to obtain panoramic H(alpha) imaging of ~200 galaxies in two nearby (32, 35 Mpc) galaxy groups NGC 4261 and NGC 5353 from the CLoGS local group survey. In rich clusters ram-pressure stripping has been shown to be very effective at removing the gas contents and quenching star formation in infalling spiral galaxies. It is much less clear how galaxies are affected by the much lower ram pressures found in galaxy groups, or if other environmental processes begin to dominate. Given that >50% of galaxies in the local volume reside in groups, it is vital we gain new insights into which mechanisms drive the SFR-density relation in groups. The proposed H(alpha) imaging will allow us to resolve where star-formation is occuring in each galaxy. This can effectively discriminate between ram-pressure stripping characterized by truncated H(alpha) disks, the much gentler starvation mechanism which produces anemic spirals, and nuclear star-bursts triggered by low-velocity encounters which should be most frequent in groups.

  19. A NuSTAR SURVEY OF NEARBY ULTRALUMINOUS INFRARED GALAXIES

    SciTech Connect

    Teng, Stacy H.; Rigby, Jane R.; Ptak, Andrew; Stern, Daniel; Alexander, D. M.; Bauer, Franz E.; Boggs, Stephen E.; Craig, William W.; Brandt, W. Niel; Luo, Bin; Christensen, Finn E.; Comastri, Andrea; Farrah, Duncan; Gandhi, Poshak; Hailey, Charles J.; Harrison, Fiona A.; Hickox, Ryan C.; Koss, Michael; and others

    2015-11-20

    We present a Nuclear Spectroscopic Telescope Array (NuSTAR), Chandra, and XMM-Newton survey of nine of the nearest ultraluminous infrared galaxies (ULIRGs). The unprecedented sensitivity of NuSTAR at energies above 10 keV enables spectral modeling with far better precision than was previously possible. Six of the nine sources observed were detected sufficiently well by NuSTAR to model in detail their broadband X-ray spectra, and recover the levels of obscuration and intrinsic X-ray luminosities. Only one source (IRAS 13120–5453) has a spectrum consistent with a Compton-thick active galactic nucleus (AGN), but we cannot rule out that a second source (Arp 220) harbors an extremely highly obscured AGN as well. Variability in column density (reduction by a factor of a few compared to older observations) is seen in IRAS 05189–2524 and Mrk 273, altering the classification of these borderline sources from Compton-thick to Compton-thin. The ULIRGs in our sample have surprisingly low observed fluxes in high-energy (>10 keV) X-rays, especially compared to their bolometric luminosities. They have lower ratios of unabsorbed 2–10 keV to bolometric luminosity, and unabsorbed 2–10 keV to mid-IR [O iv] line luminosity than do Seyfert 1 galaxies. We identify IRAS 08572+3915 as another candidate intrinsically X-ray weak source, similar to Mrk 231. We speculate that the X-ray weakness of IRAS 08572+3915 is related to its powerful outflow observed at other wavelengths.

  20. The morphology of faint galaxies in Medium Deep Survey images using WFPC2

    NASA Technical Reports Server (NTRS)

    Griffiths, R. E.; Casertano, S.; Ratnatunga, K. U.; Neuschaefer, L. W.; Ellis, R. S.; Gilmore, G. F.; Glazebrook, K.; Santiago, B.; Huchra, J. P.; Windhorst, R. A.

    1994-01-01

    First results from Hubble Space Telescope (HST) Medium Deep Survey images taken with Wide Field/Planetary Camera-2 (WFPC2) demonstrate that galaxy classifications can be reliably performed to magnitudes I814 approximately less than 22.0 in the F815W band. Published spectroscopic surveys to this depth indicate a mean redshift of bar-z approximately 0.5. We have classified over 200 galaxies in nine WFPC2 fields according to a basic morphological scheme. The majority of these faint galaxies appear to be similar to regular Hubble-sequence examples observed at low redshift. To the precision of our classification scheme, the relative proportion of spheroidal and disk systems of normal appearance is as expected from nearby samples, indicating that the bulk of the local galaxy population was in place at half the Hubble time. However, the most intriguing result is the relatively high proportion (approximately 40%) of objects which are in some way anomalous, and which may be of relevance in understanding the origin of the familiar excess population of faint galaxies established by others. These diverse objects include apparently interacting pairs whose multiple structure is only revealed with HST's angular resolution, galaxies with superluminous star-forming regions, diffuse low surface brightness galaxies of various forms, and compact galaxies. These anomalous galaxies contribute a substantial fraction of the excess counts at our limiting magnitude, and may provide insights into the 'faint blue galaxy' problem.

  1. THE XMM CLUSTER SURVEY: THE STELLAR MASS ASSEMBLY OF FOSSIL GALAXIES

    SciTech Connect

    Harrison, Craig D.; Miller, Christopher J.; Richards, Joseph W.; Deadman, Paul-James; Lloyd-Davies, E. J.; Kathy Romer, A.; Mehrtens, Nicola; Liddle, Andrew R.; Hoyle, Ben; Hilton, Matt; Stott, John P.; Capozzi, Diego; Collins, Chris A.; Sahlen, Martin; Stanford, S. Adam; Viana, Pedro T. P.

    2012-06-10

    This paper presents both the result of a search for fossil systems (FSs) within the XMM Cluster Survey and the Sloan Digital Sky Survey and the results of a study of the stellar mass assembly and stellar populations of their fossil galaxies. In total, 17 groups and clusters are identified at z < 0.25 with large magnitude gaps between the first and fourth brightest galaxies. All the information necessary to classify these systems as fossils is provided. For both groups and clusters, the total and fractional luminosity of the brightest galaxy is positively correlated with the magnitude gap. The brightest galaxies in FSs (called fossil galaxies) have stellar populations and star formation histories which are similar to normal brightest cluster galaxies (BCGs). However, at fixed group/cluster mass, the stellar masses of the fossil galaxies are larger compared to normal BCGs, a fact that holds true over a wide range of group/cluster masses. Moreover, the fossil galaxies are found to contain a significant fraction of the total optical luminosity of the group/cluster within 0.5 R{sub 200}, as much as 85%, compared to the non-fossils, which can have as little as 10%. Our results suggest that FSs formed early and in the highest density regions of the universe and that fossil galaxies represent the end products of galaxy mergers in groups and clusters.

  2. SUPERDENSE MASSIVE GALAXIES IN THE ESO DISTANT CLUSTER SURVEY (EDisCS)

    SciTech Connect

    Valentinuzzi, T.; D'onofrio, M.; Vulcani, B.; Poggianti, B. M.; Fritz, J.; Moretti, A.; Saglia, R. P.; Aragon-Salamanca, A.; Simard, L.; Sanchez-Blazquez, P.; Cava, A.; Couch, W. J.

    2010-09-20

    We find a significant number of massive and compact galaxies in clusters from the ESO Distant Clusters Survey (EDisCS) at 0.4 < z < 1. They have similar stellar masses, ages, sizes, and axial ratios to local z {approx} 0.04 compact galaxies in WIde field Nearby Galaxy clusters Survey (WINGS) clusters, and to z = 1.4-2 massive and passive galaxies found in the general field. If non-brightest cluster galaxies of all densities, morphologies, and spectral types are considered, the median size of EDisCS galaxies is only a factor 1.18 smaller than in WINGS. We show that for morphologically selected samples, the morphological evolution taking place in a significant fraction of galaxies during the last Gyr may introduce an apparent, spurious evolution of size with redshift, which is actually due to intrinsic differences in the selected samples. We conclude that the median mass-size relation of cluster galaxies does not evolve significantly from z {approx} 0.7 to z {approx} 0.04. In contrast, the masses and sizes of BCGs and galaxies with M {sub *}>4 x 10{sup 11} M {sub sun} have significantly increased by a factor of 2 and 4, respectively, confirming the results of a number of recent works on the subject. Our findings show that progenitor bias effects play an important role in the size-growth paradigm of massive and passive galaxies.

  3. A CLASSICAL MORPHOLOGICAL ANALYSIS OF GALAXIES IN THE SPITZER SURVEY OF STELLAR STRUCTURE IN GALAXIES (S{sup 4}G)

    SciTech Connect

    Buta, Ronald J.; Sheth, Kartik; Muñoz-Mateos, Juan-Carlos; Kim, Taehyun; Knapen, Johan H.; Laurikainen, Eija; Salo, Heikki; Laine, Jarkko; Comerón, Sébastien; Elmegreen, Debra; Ho, Luis C.; Zaritsky, Dennis; Hinz, Joannah L.; Courtois, Helene; Gadotti, Dimitri A.; Paz, Armando Gil de; Menéndez-Delmestre, Karín; and others

    2015-04-15

    The Spitzer Survey of Stellar Structure in Galaxies (S{sup 4}G) is the largest available database of deep, homogeneous middle-infrared (mid-IR) images of galaxies of all types. The survey, which includes 2352 nearby galaxies, reveals galaxy morphology only minimally affected by interstellar extinction. This paper presents an atlas and classifications of S{sup 4}G galaxies in the Comprehensive de Vaucouleurs revised Hubble-Sandage (CVRHS) system. The CVRHS system follows the precepts of classical de Vaucouleurs morphology, modified to include recognition of other features such as inner, outer, and nuclear lenses, nuclear rings, bars, and disks, spheroidal galaxies, X patterns and box/peanut structures, OLR subclass outer rings and pseudorings, bar ansae and barlenses, parallel sequence late-types, thick disks, and embedded disks in 3D early-type systems. We show that our CVRHS classifications are internally consistent, and that nearly half of the S{sup 4}G sample consists of extreme late-type systems (mostly bulgeless, pure disk galaxies) in the range Scd-Im. The most common family classification for mid-IR types S0/a to Sc is SA while that for types Scd to Sm is SB. The bars in these two type domains are very different in mid-IR structure and morphology. This paper examines the bar, ring, and type classification fractions in the sample, and also includes several montages of images highlighting the various kinds of “stellar structures” seen in mid-IR galaxy morphology.

  4. Determining the Intrinsic Shapes of Galaxies in the RESOLVE and ECO Surveys

    NASA Astrophysics Data System (ADS)

    Litke, Katrina; Kannappan, S.; Stark, D.; Moffett, A. J.; Eckert, K. D.; the RESOLVE Team

    2014-01-01

    We present an algorithm for determining the intrinsic shapes (edge-on axial ratios) of galaxies from the distribution of observed shapes. Galaxies are modeled as oblate ellipsoids, and the effects of nonaxisymmetry in the galaxies, seeing, and errors in measuring apparent axis ratios are included. A model grid with up to three intrinsic shapes and variable fractions of galaxies with each intrinsic shape is generated, and the models in the grid are compared to the data. We analyze likelihood distributions to identify the intrinsic shapes and the fraction of galaxies with each intrinsic shape. We test this algorithm by application to a massive early-type sample selected from the volume-limited Environmental COntext (ECO) catalog. The data are consistent with intrinsic axial ratios of 0.33 (42.5% of galaxies), 0.50 (27.9% of galaxies), and 0.72 (29.5% of galaxies). More specifically, galaxies with higher stellar masses, higher halo masses, and higher densities are found to have rounder intrinsic shapes, as expected. We describe work in progress to apply our modeling algorithm to dwarf galaxies in the volume-limited RESOLVE survey, which provides an exceptionally complete view of the low-mass galaxy population across multiple z=0 environments. This research was funded by NSF AST-0955368 and CAP REU OCI-1156614.

  5. PROBING THE INTERGALACTIC MEDIUM-GALAXY CONNECTION AT z < 0.5. I. A GALAXY SURVEY IN QSO FIELDS AND A GALAXY-ABSORBER CROSS-CORRELATION STUDY ,

    SciTech Connect

    Chen, H.-W.; Mulchaey, John S. E-mail: mulchaey@ociw.edu

    2009-08-20

    We present an imaging and spectroscopic survey of galaxies in fields around QSOs HE 0226-4110, PKS 0405-123, and PG 1216+069. The fields are selected to have ultraviolet echelle spectra available, which uncover 195 Ly{alpha} absorbers and 13 O{sub VI} absorbers along the three sightlines. We obtain robust redshifts for 1104 galaxies of rest-frame absolute magnitude M{sub R} - 5log h {approx}< -16 and at projected physical distances {rho} {approx}< 4 h{sup -1} Mpc from the QSOs. Hubble Space Telescope (HST)/WFPC2 images of the fields around PKS 0405-123 and PG 1216+069 are available for studying the optical morphologies of absorbing galaxies. Combining the absorber and galaxy data, we perform a cross-correlation study to understand the physical origin of Ly{alpha} and O{sub VI} absorbers and to constrain the properties of extended gas around galaxies. The results of our study are: (1) both strong Ly{alpha} absorbers of N(H{sub I}){>=}14 and O{sub VI} absorbers exhibit a comparable clustering amplitude as emission-line-dominated galaxies and a factor of {approx} 6 weaker amplitude than absorption-line-dominated galaxies on comoving projected distance scales of r{sub p} < 3 h{sup -1} Mpc; (2) weak Ly{alpha} absorbers of N(H{sub I})<13.5 appear to cluster very weakly around galaxies; (3) none of the absorption-line-dominated galaxies at r{sub p} {<=} 250 h{sup -1} kpc has a corresponding O{sub VI} absorber to a sensitive upper limit of W(1031) {approx}< 0.03 A, while the covering fraction of O{sub VI} absorbing gas around emission-line-dominated galaxies is found to be {kappa} {approx} 64%; and (4) high-resolution images of five O{sub VI} absorbing galaxies show that these galaxies exhibit disk-like morphologies with mildly disturbed features on the edge. Together, the data indicate that O{sub VI} absorbers arise preferentially in gas-rich galaxies. In addition, tidal debris in groups/galaxy pairs may be principally responsible for the observed O{sub VI} absorbers

  6. The Environmental Dependence of the Galaxy Luminosity Function in the ECO Survey

    NASA Astrophysics Data System (ADS)

    Andrews, Hayley; Andreas A. Berlind, Victor Calderon, Kathleen D. Eckert, Sheila J. Kannappan, Amanda J. Moffett, David V. Stark

    2016-01-01

    We study the environmental dependence of the galaxy luminosity function in the ECO survey and compare it with models that associate galaxies with dark matter halos. Specifically, we quantify the environment of each galaxy in the ECO survey using an Nth nearest neighbor distance metric, and we measure how the galaxy luminosity distribution varies from low density to high density environments. As expected, we find that luminous galaxies preferentially populate high density regions, while low luminosity galaxies preferentially populate lower density environments. We investigate whether this trend can be explained simply by the correlation of galaxy luminosity and dark matter halo mass combined with the environmental dependence of the halo mass function. In other words, we test the hypothesis that the luminosity of a galaxy depends solely on the mass of its dark matter halo and does not exhibit a residual dependence on the halo's larger environment. To test this hypothesis, we first construct mock ECO catalogs by populating dark matter halos in an N-body simulation with galaxies using a model that preserves the overall clustering strength of the galaxy population. We then assign luminosities to the mock galaxies using physically motivated models that connect luminosity to halo mass and are constrained to match the global ECO luminosity function. Finally, we impose the radial and angular selection functions of the ECO survey and repeat our environmental analysis on the mock catalogs. Though our mock catalog luminosity functions display similar qualitative trends as those from the ECO data, the trends are not in agreement quantitatively. Our results thus suggest that the simple models used to build the mocks are incomplete and that galaxy luminosity is possibly correlated with the larger scale density field.

  7. The global and local stellar mass assembly histories of galaxies from the MaNGA survey

    NASA Astrophysics Data System (ADS)

    Ibarra-Medel, Hétor J.; Sánchez,, Sebastián F.; Avila-Reese, Vladimir; Hernández-Toledo, Héctor M., J.; González, J. Jesús; Drory, Niv; Bundy, Kevin; Bizyaev, Dmitry; Cano-Díaz, Mariana; Malanushenko, Elena; Pan, Kaike; Roman-Lopes, Alexandre; Thomas, Daniel

    2016-06-01

    By means of the fossil record method implemented through Pipe3D we reconstruct the global and radial stellar mass growth histories (MGHs) of a large sample of galaxies in the mass range 10^{8.5}M⊙-10^{11.5}M⊙ from the MaNGA survey. We find that: (1) The main driver of the global MGHs is mass, with more massive galaxies assembling their masses earlier (downsizing). (2) For most galaxies in their late evolutionary stages, the innermost regions formed earlier than the outermost ones (inside-out). This behaviour is stronger for blue/late-type galaxies.

  8. EXTREMELY ISOLATED EARLY-TYPE GALAXIES IN THE SLOAN DIGITAL SKY SURVEY. I. THE SAMPLE

    SciTech Connect

    Fuse, C.; Marcum, P.; Fanelli, M. E-mail: pamela.m.marcum@nasa.gov

    2012-08-15

    We describe the properties of a sample of extremely isolated early-type galaxies (IEGs) selected from the spectroscopic Sloan Digital Sky Survey. Sample galaxies are isolated from nearest neighbors more luminous than M{sub V} = -16.5 by a minimum distance corresponding to 2.5 Mpc and 350 km s{sup -1} in redshift space. The candidate IEGs exhibit a number of unusual features as compared to bulge-dominated galaxies in cluster and group environments, including fainter luminosities, blue colors suggesting possible recent star formation, and smaller physical sizes. The paper is the first in a series analyzing this isolated galaxy sample.

  9. Maximum likelihood method for fitting the Fundamental Plane of the 6dF Galaxy Survey

    NASA Astrophysics Data System (ADS)

    Magoulas, C.; Colless, M.; Jones, D.; Springob, C.; Mould, J.

    2010-04-01

    We have used over 10,000 early-type galaxies from the 6dF Galaxy Survey (6dFGS) to construct the Fundamental Plane across the optical and near-infrared passbands. We demonstrate that a maximum likelihood fit to a multivariate Gaussian model for the distribution of galaxies in size, surface brightness and velocity dispersion can properly account for selection effects, censoring and observational errors, leading to precise and unbiased parameters for the Fundamental Plane and its intrinsic scatter. This method allows an accurate and robust determination of the dependencies of the Fundamental Plane on variations in the stellar populations and environment of early-type galaxies.

  10. The VERITAS Survey of the Cygnus Region of the Galaxy

    NASA Astrophysics Data System (ADS)

    Popkow, Alexis; Aune, Taylor; Ong, Rene A.; Ward, John E

    2014-08-01

    VERITAS (Very Energetic Radiation Imaging Telescope Array System) is an array of four 12 m diameter Imaging Atmospheric Cherenkov Telescopes (IACTs) located at Mt Hopkins, AZ. From 2007 to 2009 VERITAS undertook an extensive survey of the Cygnus region from 67 to 82 degrees Galactic longitude and from -1 to 4 degrees in Galactic latitude. This is a region with many promising Very High Energy (VHE) gamma-ray candidates such as supernova remnants, pulsar wind nebulae, high mass X-ray binaries and massive star clusters including previously detected VHE gamma-ray sources and dozens of GeV gamma-ray sources (detected by the Fermi-LAT). Along with the initial 140 hours of observations, there are over 150 hrs (a total of 294 hours after cuts for bad weather) of follow-up pointed VERITAS observations in the region that we are analyzing with updated analysis techniques. Here we present the current status of this analysis, and of an analysis of over five years of Fermi-LAT data in the region. Using a cross correlation of these results we can motivate continued observations in this active region of the Galaxy, and will incorporate multi-wavelength perspectives into a future results paper.

  11. The Stripe 82 Massive Galaxy Project - II. Stellar mass completeness of spectroscopic galaxy samples from the Baryon Oscillation Spectroscopic Survey

    NASA Astrophysics Data System (ADS)

    Leauthaud, Alexie; Bundy, Kevin; Saito, Shun; Tinker, Jeremy; Maraston, Claudia; Tojeiro, Rita; Huang, Song; Brownstein, Joel R.; Schneider, Donald P.; Thomas, Daniel

    2016-04-01

    The Baryon Oscillation Spectroscopic Survey (BOSS) has collected spectra for over one million galaxies at 0.15 < z < 0.7 over a volume of 15.3 Gpc3 (9376 deg2) - providing us an opportunity to study the most massive galaxy populations with vanishing sample variance. However, BOSS samples are selected via complex colour cuts that are optimized for cosmology studies, not galaxy science. In this paper, we supplement BOSS samples with photometric redshifts from the Stripe 82 Massive Galaxy Catalog and measure the total galaxy stellar mass function (SMF) at z ˜ 0.3 and z ˜ 0.55. With the total SMF in hand, we characterize the stellar mass completeness of BOSS samples. The high-redshift CMASS (constant mass) sample is significantly impacted by mass incompleteness and is 80 per cent complete at log 10(M*/M⊙) > 11.6 only in the narrow redshift range z = [0.51, 0.61]. The low-redshift LOWZ sample is 80 per cent complete at log 10(M*/M⊙) > 11.6 for z = [0.15, 0.43]. To construct mass complete samples at lower masses, spectroscopic samples need to be significantly supplemented by photometric redshifts. This work will enable future studies to better utilize the BOSS samples for galaxy-formation science.

  12. The Subaru FMOS galaxy redshift survey (FastSound). II. The emission line catalog and properties of emission line galaxies

    NASA Astrophysics Data System (ADS)

    Okada, Hiroyuki; Totani, Tomonori; Tonegawa, Motonari; Akiyama, Masayuki; Dalton, Gavin; Glazebrook, Karl; Iwamuro, Fumihide; Ohta, Kouji; Takato, Naruhisa; Tamura, Naoyuki; Yabe, Kiyoto; Bunker, Andrew J.; Goto, Tomotsugu; Hikage, Chiaki; Ishikawa, Takashi; Okumura, Teppei; Shimizu, Ikkoh

    2016-06-01

    We present basic properties of ˜3300 emission line galaxies detected by the FastSound survey, which are mostly Hα emitters at z ˜ 1.2-1.5 in the total area of about 20 deg2, with the Hα flux sensitivity limit of ˜1.6 × 10-16 erg cm-2 s-1 at 4.5 σ. This paper presents the catalog of the FastSound emission lines and galaxies, which is open to the public. We also present basic properties of typical FastSound Hα emitters, which have Hα luminosities of 1041.8-1043.3 erg s-1, star formation rates (SFRs) of 20-500 M⊙ yr-1, and stellar masses of 1010.0-1011.3 M⊙. The 3D distribution maps for the four fields of Canada-France-Hawaii Telescope Legacy Survey (CFHTLS) W1-4 are presented, clearly showing large scale clustering of galaxies at the scale of ˜100-600 comoving Mpc. Based on 1105 galaxies with detections of multiple emission lines, we estimate that the contamination of non-Hα lines is about 4% in the single-line emission galaxies, which is mostly [O III]λ5007. This contamination fraction is also confirmed by the stacked spectrum of all the FastSound spectra, in which Hα, [N II]λλ6548,6583, [S II]λλ6717,6731, and [O I]λλ6300,6364 are seen.

  13. The SAMI Galaxy Survey: can we trust aperture corrections to predict star formation?

    NASA Astrophysics Data System (ADS)

    Richards, S. N.; Bryant, J. J.; Croom, S. M.; Hopkins, A. M.; Schaefer, A. L.; Bland-Hawthorn, J.; Allen, J. T.; Brough, S.; Cecil, G.; Cortese, L.; Fogarty, L. M. R.; Gunawardhana, M. L. P.; Goodwin, M.; Green, A. W.; Ho, I.-T.; Kewley, L. J.; Konstantopoulos, I. S.; Lawrence, J. S.; Lorente, N. P. F.; Medling, A. M.; Owers, M. S.; Sharp, R.; Sweet, S. M.; Taylor, E. N.

    2016-01-01

    In the low-redshift Universe (z < 0.3), our view of galaxy evolution is primarily based on fibre optic spectroscopy surveys. Elaborate methods have been developed to address aperture effects when fixed aperture sizes only probe the inner regions for galaxies of ever decreasing redshift or increasing physical size. These aperture corrections rely on assumptions about the physical properties of galaxies. The adequacy of these aperture corrections can be tested with integral-field spectroscopic data. We use integral-field spectra drawn from 1212 galaxies observed as part of the SAMI Galaxy Survey to investigate the validity of two aperture correction methods that attempt to estimate a galaxy's total instantaneous star formation rate. We show that biases arise when assuming that instantaneous star formation is traced by broad-band imaging, and when the aperture correction is built only from spectra of the nuclear region of galaxies. These biases may be significant depending on the selection criteria of a survey sample. Understanding the sensitivities of these aperture corrections is essential for correct handling of systematic errors in galaxy evolution studies.

  14. VizieR Online Data Catalog: HI survey of polar ring galaxies. II. (Huchtmeier 1997)

    NASA Astrophysics Data System (ADS)

    Huchtmeier, W. K.

    1997-02-01

    We present the results of a neutral hydrogen survey conducted with the 100-m radiotelescope at Effelsberg of 44 northern objects in the polar-ring galaxy atlas of Whitmore et al. (1990AJ....100.1489W). These observations were performed to complement the Green Bank observations of polar-ring galaxies (Paper I, 1994AJ....107...99R). We detected 29 of these above our detection limit of a few mJy. The relative content of neutral hydrogen (MHI/LB) of the early-type galaxies (E, S0) in this sample is significantly higher than for galaxies of the same morphological types from comparison samples, i.e. for elliptical galaxies MHI/LB=0.17+/-0.09 and for S0 galaxies MHI/LB=0.75+/-0.13 which is about 6 times the mean value from the comparison samples for the same morphological types. (2 data files).

  15. Mapping the Galaxy Color–Redshift Relation: Optimal Photometric Redshift Calibration Strategies for Cosmology Surveys

    NASA Astrophysics Data System (ADS)

    Masters, Daniel; Capak, Peter; Stern, Daniel; Ilbert, Olivier; Salvato, Mara; Schmidt, Samuel; Longo, Giuseppe; Rhodes, Jason; Paltani, Stephane; Mobasher, Bahram; Hoekstra, Henk; Hildebrandt, Hendrik; Coupon, Jean; Steinhardt, Charles; Speagle, Josh; Faisst, Andreas; Kalinich, Adam; Brodwin, Mark; Brescia, Massimo; Cavuoti, Stefano

    2015-11-01

    Calibrating the photometric redshifts of ≳109 galaxies for upcoming weak lensing cosmology experiments is a major challenge for the astrophysics community. The path to obtaining the required spectroscopic redshifts for training and calibration is daunting, given the anticipated depths of the surveys and the difficulty in obtaining secure redshifts for some faint galaxy populations. Here we present an analysis of the problem based on the self-organizing map, a method of mapping the distribution of data in a high-dimensional space and projecting it onto a lower-dimensional representation. We apply this method to existing photometric data from the COSMOS survey selected to approximate the anticipated Euclid weak lensing sample, enabling us to robustly map the empirical distribution of galaxies in the multidimensional color space defined by the expected Euclid filters. Mapping this multicolor distribution lets us determine where—in galaxy color space—redshifts from current spectroscopic surveys exist and where they are systematically missing. Crucially, the method lets us determine whether a spectroscopic training sample is representative of the full photometric space occupied by the galaxies in a survey. We explore optimal sampling techniques and estimate the additional spectroscopy needed to map out the color–redshift relation, finding that sampling the galaxy distribution in color space in a systematic way can efficiently meet the calibration requirements. While the analysis presented here focuses on the Euclid survey, similar analysis can be applied to other surveys facing the same calibration challenge, such as DES, LSST, and WFIRST.

  16. MAPPING THE GALAXY COLOR–REDSHIFT RELATION: OPTIMAL PHOTOMETRIC REDSHIFT CALIBRATION STRATEGIES FOR COSMOLOGY SURVEYS

    SciTech Connect

    Masters, Daniel; Steinhardt, Charles; Faisst, Andreas; Capak, Peter; Stern, Daniel; Rhodes, Jason; Ilbert, Olivier; Salvato, Mara; Schmidt, Samuel; Longo, Giuseppe; Paltani, Stephane; Coupon, Jean; Mobasher, Bahram; Hoekstra, Henk; Hildebrandt, Hendrik; Speagle, Josh; Kalinich, Adam; Brodwin, Mark; Brescia, Massimo; Cavuoti, Stefano

    2015-11-01

    Calibrating the photometric redshifts of ≳10{sup 9} galaxies for upcoming weak lensing cosmology experiments is a major challenge for the astrophysics community. The path to obtaining the required spectroscopic redshifts for training and calibration is daunting, given the anticipated depths of the surveys and the difficulty in obtaining secure redshifts for some faint galaxy populations. Here we present an analysis of the problem based on the self-organizing map, a method of mapping the distribution of data in a high-dimensional space and projecting it onto a lower-dimensional representation. We apply this method to existing photometric data from the COSMOS survey selected to approximate the anticipated Euclid weak lensing sample, enabling us to robustly map the empirical distribution of galaxies in the multidimensional color space defined by the expected Euclid filters. Mapping this multicolor distribution lets us determine where—in galaxy color space—redshifts from current spectroscopic surveys exist and where they are systematically missing. Crucially, the method lets us determine whether a spectroscopic training sample is representative of the full photometric space occupied by the galaxies in a survey. We explore optimal sampling techniques and estimate the additional spectroscopy needed to map out the color–redshift relation, finding that sampling the galaxy distribution in color space in a systematic way can efficiently meet the calibration requirements. While the analysis presented here focuses on the Euclid survey, similar analysis can be applied to other surveys facing the same calibration challenge, such as DES, LSST, and WFIRST.

  17. Galaxies

    SciTech Connect

    Not Available

    1981-01-01

    Normal galaxies, radio galaxies, and Seyfert galaxies are considered. The large magellanic cloud and the great galaxy in Andromedia are highlighted. Quasars and BL lacertae objects are also discussed and a review of the spectral observations of all of these galaxies and celestial objects is presented.

  18. Aperture corrections for disk galaxy properties derived from the CALIFA survey. Balmer emission lines in spiral galaxies

    NASA Astrophysics Data System (ADS)

    Iglesias-Páramo, J.; Vílchez, J. M.; Galbany, L.; Sánchez, S. F.; Rosales-Ortega, F. F.; Mast, D.; García-Benito, R.; Husemann, B.; Aguerri, J. A. L.; Alves, J.; Bekeraité, S.; Bland-Hawthorn, J.; Catalán-Torrecilla, C.; de Amorim, A. L.; de Lorenzo-Cáceres, A.; Ellis, S.; Falcón-Barroso, J.; Flores, H.; Florido, E.; Gallazzi, A.; Gomes, J. M.; González Delgado, R. M.; Haines, T.; Hernández-Fernández, J. D.; Kehrig, C.; López-Sánchez, A. R.; Lyubenova, M.; Marino, R. A.; Mollá, M.; Monreal-Ibero, A.; Mourão, A.; Papaderos, P.; Rodrigues, M.; Sánchez-Blázquez, P.; Spekkens, K.; Stanishev, V.; van de Ven, G.; Walcher, C. J.; Wisotzki, L.; Zibetti, S.; Ziegler, B.

    2013-05-01

    This work investigates the effect of the aperture size on derived galaxy properties for which we have spatially-resolved optical spectra. We focus on some indicators of star formation activity and dust attenuation for spiral galaxies that have been widely used in previous work on galaxy evolution. We investigated 104 spiral galaxies from the CALIFA survey for which 2D spectroscopy with complete spatial coverage is available. From the 3D cubes we derived growth curves of the most conspicuous Balmer emission lines (Hα, Hβ) for circular apertures of different radii centered at the galaxy's nucleus after removing the underlying stellar continuum. We find that the Hα flux (f(Hα)) growth curve follows a well-defined sequence with aperture radius that shows a low dispersion around the median value. From this analysis, we derived aperture corrections for galaxies in different magnitude and redshift intervals. Once stellar absorption is properly accounted for, the f(Hα)/f(Hβ) ratio growth curve shows a smooth decline, pointing toward the absence of differential dust attenuation as a function of radius. Aperture corrections as a function of the radius are provided in the interval [0.3, 2.5]R50. Finally, the Hα equivalent-width (EW(Hα)) growth curve increases with the size of the aperture and shows a very high dispersion for small apertures. This prevents us from using reliable aperture corrections for this quantity. In addition, this result suggests that separating star-forming and quiescent galaxies based on observed EW(Hα) through small apertures will probably result in low EW(Hα) star-forming galaxies begin classified as quiescent.

  19. The LEGA-C Survey: The Physics of Galaxies 7 Gyr Ago

    NASA Astrophysics Data System (ADS)

    van der Wel, A.; Noeske, K.; Bezanson, R.; Pacifici, C.; Gallazzi, A.; Franx, M.; Muñoz-Mateos, J.-C.; Bell, E. F.; Brammer, G.; Charlot, S.; Chauké, P.; Labbé, I.; Maseda, M. V.; Muzzin, A.; Rix, H.-W.; Sobral, D.; van de Sande, J.; van Dokkum, P. G.; Wild, V.; Wolf, C.

    2016-06-01

    The LEGA-C (Large Early Galaxy Census) survey is made possible by the refurbishment of the Very Large Telescope VIsible and Multi Object Spectrograph (VIMOS) instrument and the implementation by ESO of a new generation of large spectroscopic surveys. The goal is to obtain high-quality continuum spectra of thousands of galaxies with redshifts up to z = 1, with which key physical parameters that were previously inaccessible can be measured. These include star formation histories and dynamical masses, which greatly improve our insight into how galaxies form and evolve. This article coincides with the first public data release of fully reduced and calibrated spectra.

  20. VEGAS-SSS: A VST Early-Type GAlaxy Survey: Analysis of Small Stellar System

    NASA Astrophysics Data System (ADS)

    Cantiello, M.

    VEGAS-SSS is a program devoted to study the properties of small stellar systems (SSSs) around bright galaxies, built on the VEGAS survey. At completion, the survey will have collected detailed photometric information of ˜ 100 bright early-type galaxies to study the properties of diffuse light (surface brightness, colours, SBF, etc.) and the clustered light (compact stellar systems) out to previously unreached projected galactocentric radii. VEGAS-SSS will define an accurate and homogeneous dataset that will have an important legacy value for studies of the evolution and transformation processes taking place in galaxies through the fossil information provided by SSSs.

  1. GALAXIES BEHIND THE GALACTIC PLANE: FIRST RESULTS AND PERSPECTIVES FROM THE VVV SURVEY

    SciTech Connect

    Amores, E. B.; Arsenijevic, V.; Sodre, L.; Minniti, D.; Padilla, N.; Alonso, M. V.; Gurovich, S.; Diaz Tello, J.; Tollerud, E. J.; Rodriguez-Ardila, A.

    2012-11-01

    VISTA Variables in the Via Lactea (VVV) is an ESO variability survey that is performing observations in near-infrared bands (ZY JHK{sub s}) toward the Galactic bulge and part of the disk with the completeness limits at least 3 mag deeper than Two Micron All Sky Survey. In the present work, we searched in the VVV survey data for background galaxies near the Galactic plane using ZY JHK{sub s} photometry that covers 1.636 deg{sup 2}. We identified 204 new galaxy candidates by analyzing colors, sizes, and visual inspection of multi-band (ZY JHK{sub s}) images. The galaxy candidate colors were also compared with the predicted ones by star count models considering a more realistic extinction model at the same completeness limits observed by VVV. A comparison of the galaxy candidates with the expected one by Millennium simulations is also presented. Our results increase the number density of known galaxies behind the Milky Way by more than one order of magnitude. A catalog with galaxy properties including ellipticity, Petrosian radii, and ZY JHK{sub s} magnitudes is provided, as well as comparisons of the results with other surveys of galaxies toward the Galactic plane.

  2. Mapping the Galaxy Color-Redshift Relation: Optimal Photo-z Calibration Strategies for Cosmology Surveys

    NASA Astrophysics Data System (ADS)

    Masters, Daniel C.; Capak, Peter L.; Stern, Daniel; Rhodes, Jason; Mobasher, Bahram; Schmidt, Samuel; Steinhardt, Charles L.; Faisst, Andreas; Speagle, Josh S.

    2016-01-01

    A primary objective of the upcoming dark energy surveys LSST, Euclid, and WFIRST is to map the 3D distribution of matter over a significant fraction of the universe via the weak lensing cosmic shear field. Doing so will require accurate distance estimates to billions of faint galaxies, meaning that photo-z's will be essential for the ultimate scientific success of these missions. Because galaxy colors drive photo-z estimates, spectroscopic calibration samples must at least be representative in color. Here we present a technique, based on the self-organizing map (Kohonen 1990), to map the empirical distribution of galaxies in the high-dimensional color space of a given survey. We apply the technique to Euclid-like data for ~131k galaxies from the COSMOS survey, allowing us to determine where - in galaxy color space - spectroscopic coverage exists and where it is systematically missing. We show that the mapping technique lets us develop efficient spectroscopic sampling strategies to measure the color-redshift relation by focusing effort on poorly constrained regions of multicolor space. We discuss the nature of the galaxies in un-sampled regions of galaxy color space, and show that a fiducial survey with Keck (making use of LRIS, DEIMOS, and MOSFIRE) could meet the Euclid calibration requirements in ~40 nights of observing.

  3. The BLUEDISK Survey: molecular gas distribution and scaling relations in the context of galaxy evolution

    NASA Astrophysics Data System (ADS)

    Cormier, D.; Bigiel, F.; Wang, J.; Pety, J.; Usero, A.; Roychowdhury, S.; Carton, D.; Hulst, J. M. van der; Józsa, G. I. G.; García, M. Gonzalez; Saintonge, A.

    2016-08-01

    One of the key goals of the BLUEDISK survey is to characterize the impact of gas accretion in disc galaxies in the context of galaxy evolution. It contains 50 disc galaxies in the stellar mass range 1010 - 1011 M⊙, of which half are bluer and more H I-rich galaxies than their H I-normal (control) counterparts. In this paper, we investigate how ongoing disc growth affects the molecular gas distribution and the star-formation efficiency in these galaxies. We present 12CO observations from the IRAM 30-m telescope in 26 galaxies of the BLUEDISK survey. We compare the amount and spatial distribution of the molecular gas to key quantities such as atomic gas, stellar mass and surface density, star-formation rate and metallicity. We analyse the star-formation rate per unit gas (SFR/H I and SFR/H2) and relate all those parameters to general galaxy properties (H I-rich/control disc, morphology, etc.). We find that the H I-rich galaxies have similar H2 masses as the control galaxies. In their centres, H I-rich galaxies have lower H2/H I ratios and marginally shorter molecular gas depletion times. However, the main differences between the two samples occur in the outer parts of the discs, with the H I-rich galaxies having slightly smaller CO discs (relative to the optical radius R25) and steeper CO and metallicity gradients than the control galaxies. The ongoing accretion of H I at large radii has thus not led to an appreciable growth of the CO discs in our sample. Based on depletion times, we estimate that this gas will contribute to star formation on time-scales of at least 5 Gyr.

  4. The GHOSTS survey - II. The diversity of halo colour and metallicity profiles of massive disc galaxies

    NASA Astrophysics Data System (ADS)

    Monachesi, Antonela; Bell, Eric F.; Radburn-Smith, David J.; Bailin, Jeremy; de Jong, Roelof S.; Holwerda, Benne; Streich, David; Silverstein, Grace

    2016-04-01

    We study the stellar halo colour properties of six nearby massive highly inclined disc galaxies using Hubble space telescope Advanced Camera for Surveys and Wide Field Camera 3 observations in both F606W and F814W filters from the GHOSTS (Galaxy Halos, Outer disks, Substructure, Thick disks, and Star clusters) survey. The observed fields probe the stellar outskirts out to projected distances of ˜50-70 kpc from their galactic centre along the minor axis. The 50 per cent completeness levels of the colour-magnitude diagrams are typically at 2 mag below the tip of the red giant branch (RGB). We find that all galaxies have extended stellar haloes out to ˜50 kpc and two out to ˜70 kpc. We determined the halo colour distribution and colour profile for each galaxy using the median colours of stars in the RGB. Within each galaxy, we find variations in the median colours as a function of radius which likely indicates population variations, reflecting that their outskirts were built from several small accreted objects. We find that half of the galaxies (NGC 0891, NGC 4565, and NGC 7814) present a clear negative colour gradient in their haloes, reflecting a declining metallicity; the other have no significant colour or population gradient. In addition, notwithstanding the modest sample size of galaxies, there is no strong correlation between their halo colour/metallicity or gradient with galaxy's properties such as rotational velocity or stellar mass. The diversity in halo colour profiles observed in the GHOSTS galaxies qualitatively supports the predicted galaxy-to-galaxy scatter in halo stellar properties, a consequence of the stochasticity inherent in the assembling history of galaxies.

  5. The Optical Luminosity Function of Void Galaxies in the SDSS and ALFALFA Surveys

    NASA Astrophysics Data System (ADS)

    Moorman, Crystal M.; Vogeley, Michael S.; Hoyle, Fiona; Pan, Danny C.; Haynes, Martha P.; Giovanelli, Riccardo

    2015-09-01

    We measure the r-band galaxy luminosity function (LF) across environments over the redshift range 0 < z < 0.107 using the Sloan Digital Sky Survey (SDSS). We divide our sample into galaxies residing in large-scale voids (void galaxies) and those residing in denser regions (wall galaxies). The best-fitting Schechter parameters for void galaxies are {log}{{{Φ }}}*=-3.40+/- 0.03 log(Mpc-3), {M}* = -19.88 ± 0.05, and α = -1.20 ± 0.02. For wall galaxies, the best-fitting parameters are {log}{{{Φ }}}*=-2.86+/- 0.02 log(Mpc-3), {M}* = -20.80 ± 0.03, and α = -1.16 ± 0.01. We find a shift in the characteristic magnitude, {M}*, toward fainter magnitudes for void galaxies and find no significant difference between the faint-end slopes of the void and wall galaxy LFs. We investigate how low-surface-brightness selection effects can affect the galaxy LF. To attempt to examine a sample of galaxies that is relatively free of surface-brightness selection effects, we compute the optical galaxy LF of galaxies detected by the blind H i survey Arecibo Legacy Fast ALFA (ALFALFA). We find that the global LF of the ALFALFA sample is not well fit by a Schechter function because of the presence of a wide dip in the LF around Mr = -18 and an upturn at fainter magnitudes (α ˜ -1.47). We compare the H i selected r-band LF to various LFs of optically selected populations to determine where the H i selected optical LF obtains its shape. We find that sample selection plays a large role in determining the shape of the LF.

  6. Evolution of Group Galaxies from the First Red-Sequence Cluster Survey

    NASA Astrophysics Data System (ADS)

    Li, I. H.; Yee, H. K. C.; Hsieh, B. C.; Gladders, M.

    2012-04-01

    We study the evolution of the red-galaxy fraction (f red) in 905 galaxy groups with 0.15 <= z < 0.52. The galaxy groups are identified by the "probability friends-of-friends" algorithm from the first Red-Sequence Cluster Survey (RCS1) photometric-redshift sample. There is a high degree of uniformity in the properties of the red sequence of the group galaxies, indicating that the luminous red-sequence galaxies in the groups are already in place by z ~ 0.5 and that they have a formation epoch of z >~ 2. In general, groups at lower redshifts exhibit larger f red than those at higher redshifts, showing a group Butcher-Oemler effect. We investigate the evolution of f red by examining its dependence on four parameters, one of which can be classified as intrinsic and three of which can be classified as environmental: galaxy stellar mass (M *), total group stellar mass (M *, grp, a proxy for group halo mass), normalized group-centric radius (r grp), and local galaxy density (Σ5). We find that M * is the dominant parameter such that there is a strong correlation between f red and galaxy stellar mass. Furthermore, the dependence of f red on the environmental parameters is also a strong function of M *. Massive galaxies (M * >~ 1011 M ⊙) show little dependence of f red on r grp, M *, grp, and Σ5 over the redshift range. The dependence of f red on these parameters is primarily seen for galaxies with lower masses, especially for M * <~ 1010.6 M ⊙. We observe an apparent "group down-sizing" effect, in that galaxies in lower-mass halos, after controlling for galaxy stellar mass, have lower f red. We find a dependence of f red on both r grp and Σ5 after the other parameters are controlled. At a fixed r grp, there is a significant dependence of f red on Σ5, while r grp gradients of f red are seen for galaxies in similar Σ5 regions. This indicates that galaxy group environment has a residual effect over that of local galaxy density (or vice versa), and both parameters need

  7. A Multiwavelength Study of Millimeter Galaxies in the Bolocam-COSMOS Survey

    NASA Astrophysics Data System (ADS)

    Aguirre, James E.; Bolocam-COSMOS Collaboration

    2006-12-01

    We present a multiwavelength study of galaxies detected in a 1.1 mm Bolocam survey of the center 940 square arcminutes of the COSMOS HST Treasury field. The Bolocam survey reached an RMS noise level (filtered for point sources) of 1.9 mJy/beam. We compare the detections with overlapping AzTEC and MAMBO surveys, and examine the radio to X-ray properties of these galaxies using the rich datasets available in the field. Particular attention is given to Spitzer IRAC and MIPS counterparts from the S-COSMOS survey.

  8. The LMT Galaxies' 3 mm Spectroscopic Survey: First Results

    NASA Astrophysics Data System (ADS)

    Rosa González, D.; Schloerb, P.; Vega, O.; Hunt, L.; Narayanan, G.; Calzetti, D.; Yun, M.; Terlevich, E.; Terlevich, R.; Mayya, Y. D.; Chávez, M.; Montaña, A.; Pérez García, A. M.

    2014-09-01

    The molecular phase of the interstellar medium (ISM) in galaxies offers fundamental insight for understanding star-formation processes and how stellar feedback affects the nuclear activity of certain galaxies. We present here Large Millimeter Telescope spectra obtained with the Redshift Search Receiver, a spectrograph that covers simultaneously the 3 mm band from 74 to 111 GHz with a spectral resolution of around 100 km/s. Our selected galaxies, have been detected previously in HCN, and have different degrees of nuclear activity — one normal galaxy (NGC 6946), the starburst prototype (M82) and two %ultraluminous infrared galaxies (ULIRGs, IRAS 17208-0014 and Mrk 231). We plotted our data in the HCO+/HCN vs. HCN/13CO diagnostic diagram finding that NGC 6946 and M82 are located close to other normal galaxies; and that both IRAS 17208-0014 and Mrk 231 are close to the position of the well known ULIRG Arp 220 reported by Snell et al. (2011). We found that in Mrk 231 - a galaxy with a well known active galactic nucleus - the HCO+/HCN ratio is similar to the ratio observed in normal galaxies.

  9. Dark energy properties from large future galaxy surveys

    SciTech Connect

    Basse, Tobias; Bjælde, Ole Eggers; Hannestad, Steen; Hamann, Jan; Wong, Yvonne Y.Y. E-mail: oeb@phys.au.dk E-mail: sth@phys.au.dk

    2014-05-01

    We perform a detailed forecast on how well a Euclid-like survey will be able to constrain dark energy and neutrino parameters from a combination of its cosmic shear power spectrum, galaxy power spectrum, and cluster mass function measurements. We find that the combination of these three probes vastly improves the survey's potential to measure the time evolution of dark energy. In terms of a dark energy figure-of-merit defined as (σ(w{sub p})σ(w{sub a})){sup −1}, we find a value of 690 for Euclid-like data combined with Planck-like measurements of the cosmic microwave background anisotropies in a 10-dimensional cosmological parameter space, assuming a ΛCDM fiducial cosmology. For the more commonly used 7-parameter model, we find a figure-of-merit of 1900 for the same data combination. We consider also the survey's potential to measure dark energy perturbations in models wherein the dark energy is parameterised as a fluid with a nonstandard non-adiabatic sound speed, and find that in an optimistic scenario in which w{sub 0} deviates from -1 by as much as is currently observationally allowed, models with c-circumflex {sub s}{sup 2} = 10{sup −6} and c-circumflex {sub s}{sup 2} = 1 can be distinguished from one another at more than 2σ significance. We emphasise that constraints on the dark energy sound speed from cluster measurements are strongly dependent on the modelling of the cluster mass function; significantly weaker sensitivities ensue if we modify our model to include fewer features of nonlinear dark energy clustering. Finally, we find that the sum of neutrino masses can be measured with a 1σ precision of 0.015 eV, even in complex cosmological models in which the dark energy equation of state varies with time. The 1σ sensitivity to the effective number of relativistic species N{sub eff}{sup ml} is approximately 0.03, meaning that the small deviation of 0.046 from 3 in the standard value of N{sub eff}{sup ml} due to non-instantaneous decoupling and

  10. VizieR Online Data Catalog: VEGAS: A VST Early-type GAlaxy Survey (Capaccioli+, 2015)

    NASA Astrophysics Data System (ADS)

    Capaccioli, M.; Spavone, M.; Grado, A.; Iodice, E.; Limatola, L.; Napolitano, N. R.; Cantiello, M.; Paolillo, M.; Romanowsky, A. J.; Forbes, D. A.; Puzia, T. H.; Raimondo, G.; Schipani, P.

    2015-11-01

    The VST Elliptical GAlaxies Survey (VEGAS) is a deep multiband (g,r,i) imaging survey of early-type galaxies in the southern hemisphere carried out with VST at the ESO Cerro Paranal Observatory (Chile). The large field of view (FOV) of the OmegaCAM mounted on VST (one square degree matched by pixels 0.21-arcsec wide), together with its high efficiency and spatial resolution (typically better than 1-arcsec; Kuijken, 2011Msngr.146....8K) allows us to map with a reasonable integration time the surface brightness of a galaxy out to isophotes encircling about 95% of the total light. Observations started in October 2011 (ESO Period 88), and since then, the survey has acquired exposures for about 20 bright galaxies (and for a wealth of companion objects in the field), for a totality of ~80h (up to Period 93). (1 data file).

  11. The SLUGGS survey: the assembly histories of individual early-type galaxies

    NASA Astrophysics Data System (ADS)

    Forbes, Duncan A.; Romanowsky, Aaron J.; Pastorello, Nicola; Foster, Caroline; Brodie, Jean P.; Strader, Jay; Usher, Christopher; Pota, Vincenzo

    2016-04-01

    Early-type (E and S0) galaxies may have assembled via a variety of different evolutionary pathways. Here, we investigate these pathways by comparing the stellar kinematic properties of 24 early-type galaxies from the SAGES Legacy Unifying Globulars and GalaxieS (SLUGGS) survey with the hydrodynamical simulations of Naab et al. In particular, we use the kinematics of starlight up to 4 effective radii (Re) as diagnostics of galaxy inner and outer regions, and assign each galaxy to one of six Naab et al. assembly classes. The majority of our galaxies (14/24) have kinematic characteristics that indicate an assembly history dominated by gradual gas dissipation and accretion of many gas-rich minor mergers. Three galaxies, all S0s, indicate that they have experienced gas-rich major mergers in their more recent past. One additional elliptical galaxy is tentatively associated with a gas-rich merger which results in a remnant galaxy with low angular momentum. Pathways dominated by gas-poor (major or minor) mergers dominate the mass growth of six galaxies. Most SLUGGS galaxies appear to have grown in mass (and size) via the accretion of stars and gas from minor mergers, with late major mergers playing a much smaller role. We find that the fraction of accreted stars correlates with the stellar mean age and metallicity gradient, but not with the slope of the total mass density profile. We briefly mention future observational and modelling approaches that will enhance our ability to accurately reconstruct the assembly histories of individual present-day galaxies.

  12. SYSTEMATIC SEARCH FOR EXTREMELY METAL-POOR GALAXIES IN THE SLOAN DIGITAL SKY SURVEY

    SciTech Connect

    Morales-Luis, A. B.; Sanchez Almeida, J.; Aguerri, J. A. L.; Munoz-Tunon, C. E-mail: jos@iac.es E-mail: jalfonso@iac.es

    2011-12-10

    We carry out a systematic search for extremely metal-poor (XMP) galaxies in the spectroscopic sample of Sloan Digital Sky Survey (SDSS) data release 7 (DR7). The XMP candidates are found by classifying all the galaxies according to the form of their spectra in a region 80 A wide around H{alpha}. Due to the data size, the method requires an automatic classification algorithm. We use k-means. Our systematic search renders 32 galaxies having negligible [N II] lines, as expected in XMP galaxy spectra. Twenty-one of them have been previously identified as XMP galaxies in the literature-the remaining 11 are new. This was established after a thorough bibliographic search that yielded only some 130 galaxies known to have an oxygen metallicity 10 times smaller than the Sun (explicitly, with 12 + log (O/H) {<=} 7.65). XMP galaxies are rare; they represent 0.01% of the galaxies with emission lines in SDSS/DR7. Although the final metallicity estimate of all candidates remains pending, strong-line empirical calibrations indicate a metallicity about one-tenth solar, with the oxygen metallicity of the 21 known targets being 12 + log (O/H) {approx_equal} 7.61 {+-} 0.19. Since the SDSS catalog is limited in apparent magnitude, we have been able to estimate the volume number density of XMP galaxies in the local universe, which turns out to be (1.32 {+-} 0.23) Multiplication-Sign 10{sup -4} Mpc{sup -3}. The XMP galaxies constitute 0.1% of the galaxies in the local volume, or {approx}0.2% considering only emission-line galaxies. All but four of our candidates are blue compact dwarf galaxies, and 24 of them have either cometary shape or are formed by chained knots.

  13. The Hector Survey: integral field spectroscopy of 100,000 galaxies

    NASA Astrophysics Data System (ADS)

    Bland-Hawthorn, J.

    2015-02-01

    In March 2013, the Sydney-AAO Multi-object Integral field spectrograph (SAMI) began a major survey of 3400 galaxies at the AAT, the largest of its kind to date. At the time of writing, over a third of the targets have been observed and the scientific impact has been immediate. The Manga galaxy survey has now started at the SDSS telescope and will target an even larger sample of nearby galaxies. In Australia, the community is now gearing up to deliver a major new facility called Hector that will allow integral field spectroscopy of 100 galaxies observed simultaneously. By the close of the decade, it will be possible to obtain integral field spectroscopy of 100,000 galaxies over 3000 square degrees of sky down to r=17 (median). Many of these objects will have HI imaging from the new ASKAP radio surveys. We discuss the motivation for such a survey and the use of new cosmological simulations that are properly matched to the integral field observations. The Hector survey will open up a new and unique parameter space for galaxy evolution studies.

  14. BRIGHTEST SATELLITE GALAXY ALIGNMENT OF SLOAN DIGITAL SKY SURVEY GALAXY GROUPS

    SciTech Connect

    Li Zhigang; Wang Yougang; Chen Xuelei; Yang Xiaohu; Xie Lizhi; Wang Xin E-mail: wangygcluster@gmail.com E-mail: lzxie@bao.ac.cn E-mail: wangxin@pha.jhu.edu

    2013-05-01

    We study the alignment signal between the distribution of the brightest satellite galaxies (BSGs) and the major axes of their host groups using the Sloan Digital Sky Survey group catalog constructed by Yang et al. After correcting for the effect of group ellipticity, a statistically significant ({approx}5{sigma}) major-axis alignment is detected and the alignment angle is found to be 43. Degree-Sign 0 {+-} 0. Degree-Sign 4. More massive and richer groups show a stronger BSG alignment. The BSG alignment around blue brightest central galaxies (BCGs) is slightly stronger than that around red BCGs. Red BSGs have a much stronger major-axis alignment than blue BSGs. Unlike BSGs, other satellites do not show very significant alignment with their group's major axis. We further explore BSG alignment using the semi-analytic model (SAM) constructed by Guo et al. In general, we found good agreement of the model with observations: BSGs in the SAM show a strong major-axis alignment that depends on group mass and richness in the same way as in observations and none of the other satellites exhibit prominent alignment. However, a discrepancy also exists in that the SAM shows a BSG color dependence opposite of that in observations, which is most probably induced by a missing large-scale environment ingredient in the SAM. The combination of two popular scenarios can explain the BSG alignment we detected. First, satellites merged into the group along the surrounding filaments, which are strongly aligned with the major axis of the group. Second, BSGs entered their host group more recently than other satellites, so they have preserved more information about their assembling history and major-axis alignment. In the SAM, we found positive evidence for the second scenario in the fact that BSGs merged into groups statistically more recently than other satellites. We also found that most of the BSGs (80%) were BCGs before they merged into groups and earlier merging BSGs tend to be closer to

  15. Confirmation of a galaxy cluster hidden behind the Galactic bulge using the VVV survey

    NASA Astrophysics Data System (ADS)

    Coldwell, Georgina; Alonso, Sol; Duplancic, Fernanda; Hempel, Maren; Ivanov, Valentin D.; Minniti, Dante

    2014-09-01

    Context. Suzaku and Chandra X-ray observations detected a new cluster of galaxies, Suzaku J1759-3450, at a redshift z = 0.13. It is located behind the Milky Way, and the high Galactic dust extinction renders it nearly invisible at optical wavelengths. Aims: We attempt here to confirm the galaxy cluster with near-infrared imaging observations and to characterize its central member galaxies. Methods: Images from the VVV survey were used to detect candidate member galaxies of Suzaku J1759-3450 within the central region of the cluster up to 350 kpc from the X-ray peak emission. Color-magnitude diagrams, color-color diagrams, and morphology criteria allowed us to select the galaxies among the numerous foreground sources. Results: Fifteen candidate cluster members were found very close to a modeled red-sequence at the redshift of the cluster. Five members are extremely bright, and one is possibly a cD galaxy. The asymmetry in the spatial distribution of the galaxies with respect to the X-ray peak emission is an indicator that this cluster is still suffering a virialization process. Conclusions: Our investigation of Suzaku J1759-3450 demonstrates the potential of the VVV survey to study the hidden population of galaxies in the zone of avoidance.

  16. Mocking the ECO and RESOLVE Surveys: Probing the Environmental Dependencies of Galaxy Properties

    NASA Astrophysics Data System (ADS)

    Berlind, Andreas A.; Florez, Jonathan; Calderon, Victor; Sinha, Manodeep; Moffett, Amanda J.; Eckert, Kathleen D.; Kannappan, Sheila; Stark, David; Baker, Ashley; RESOLVE Team

    2016-01-01

    We present mock catalogs for the RESOLVE survey and the associated Environmental COntext (ECO) catalog. The mock catalogs are constructed by populating dark matter halos in cosmological N-body simulations with galaxies using prescriptions that yield the same joint distributions of galaxy properties and overall clustering strength as seen in the ECO catalog. Specifically, we use a combination of Halo Occupation Distribution (HOD), Conditional Luminosity Function (CLF), and abundance matching techniques to connect mock galaxies to halos and we adopt different assumptions of how observable properties correlate with the properties of the underlying halos. We use the resulting mock catalogs to assess systematic errors in environmental metrics, such as errors in the inferred masses of galaxy groups that are due to group over-merging or fragmentation. We also use the mock catalogs to compare to an interesting trend that we find for galaxies that live in the 10% lowest density environments in ECO and RESOLVE. In the observations, we find that, at fixed stellar or baryonic mass, these galaxies in low density regions are bluer, more star forming, and more gas rich than galaxies residing in higher density environments. Some mock-making prescriptions are more successful than others in matching this observed trend, highlighting the power of mock catalogs to connect observations to the underlying relationships between galaxies and their dark matter halos. The RESOLVE survey is supported by NSF grant AST-0955368.

  17. The SAMI Pilot Survey: stellar kinematics of galaxies in Abell 85, 168 and 2399

    NASA Astrophysics Data System (ADS)

    Fogarty, L. M. R.; Scott, N.; Owers, M. S.; Croom, S. M.; Bekki, K.; Houghton, R. C. W.; van de Sande, J.; D'Eugenio, F.; Cecil, G. N.; Colless, M. M.; Bland-Hawthorn, J.; Brough, S.; Cortese, L.; Davies, R. L.; Jones, D. H.; Pracy, M.; Allen, J. T.; Bryant, J. J.; Goodwin, M.; Green, A. W.; Konstantopoulos, I. S.; Lawrence, J. S.; Lorente, N. P. F.; Richards, S.; Sharp, R. G.

    2015-12-01

    We present the SAMI Pilot Survey, consisting of integral field spectroscopy of 106 galaxies across three galaxy clusters, Abell 85, Abell 168 and Abell 2399. The galaxies were selected by absolute magnitude to have Mr < -20.25 mag. The survey, using the Sydney-AAO Multi-object Integral field spectrograph (SAMI), comprises observations of galaxies of all morphological types with 75 per cent of the sample being early-type galaxies (ETGs) and 25 per cent being late-type galaxies (LTGs). Stellar velocity and velocity dispersion maps are derived for all 106 galaxies in the sample. The λR parameter, a proxy for the specific stellar angular momentum, is calculated for each galaxy in the sample. We find a trend between λR and galaxy concentration such that LTGs are less concentrated higher angular momentum systems, with the fast-rotating ETGs (FRs) more concentrated and lower in angular momentum. This suggests that some dynamical processes are involved in transforming LTGs to FRs, though a significant overlap between the λR distributions of these classes of galaxies implies that this is just one piece of a more complicated picture. We measure the kinematic misalignment angle, Ψ, for the ETGs in the sample, to probe the intrinsic shapes of the galaxies. We find the majority of FRs (83 per cent) to be aligned, consistent with them being oblate spheroids (i.e. discs). The slow rotating ETGs (SRs), on the other hand, are significantly more likely to show kinematic misalignment (only 38 per cent are aligned). This confirms previous results that SRs are likely to be mildly triaxial systems.

  18. THE SLACS SURVEY. VIII. THE RELATION BETWEEN ENVIRONMENT AND INTERNAL STRUCTURE OF EARLY-TYPE GALAXIES

    SciTech Connect

    Treu, Tommaso; Gavazzi, Raphael; Gorecki, Alexia; Marshall, Philip J.; Koopmans, Leon V. E.; Bolton, Adam S.; Moustakas, Leonidas A.; Burles, Scott E-mail: pjm@physics.ucsb.edu E-mail: koopmans@astro.rug.nl E-mail: leonidas@jpl.nasa.gov

    2009-01-01

    We study the relation between the internal structure of early-type galaxies and their environment using 70 strong gravitational lenses from the SLACS Survey. The Sloan Digital Sky Survey (SDSS) database is used to determine two measures of overdensity of galaxies around each lens-the projected number density of galaxies inside the tenth nearest neighbor ({sigma}{sub 10}) and within a cone of radius one h{sup -1} Mpc (D {sub 1}). Our main results are as follows. (1) The average overdensity is somewhat larger than unity, consistent with lenses preferring overdense environments as expected for massive early-type galaxies (12/70 lenses are in known groups/clusters). (2) The distribution of overdensities is indistinguishable from that of 'twin' nonlens galaxies selected from SDSS to have the same redshift and stellar velocity dispersion {sigma}{sub *}. Thus, within our errors, lens galaxies are an unbiased population, and the SLACS results can be generalized to the overall population of early-type galaxies. (3) Typical contributions from external mass distribution are no more than a few percent in local mass density, reaching 10-20% ({approx}0.05-0.10 external convergence) only in the most extreme overdensities. (4) No significant correlation between overdensity and slope of the mass-density profile of the lens galaxies is found. (5) Satellite galaxies (those with a more luminous companion) have marginally steeper mass-density profiles (as quantified by f {sub SIE} = {sigma}{sub *}/{sigma}{sub SIE} = 1.12 {+-} 0.05 versus 1.01 {+-} 0.01) and smaller dynamically normalized mass enclosed within the Einstein radius ({delta}log M {sub Ein}/M {sub dim} differs by -0.09 {+-} 0.03 dex) than central galaxies (those without). This result suggests that tidal stripping may affect the mass structure of early-type galaxies down to kpc scales probed by strong lensing, when they fall into larger structures.

  19. A SiO 2-1 SURVEY TOWARD GAS-RICH ACTIVE GALAXIES

    SciTech Connect

    Wang, Junzhi; Zhang, Jiangshui; Shi, Yong; Zhang, Zhiyu

    2013-12-01

    In order to study the feedback from active galactic nuclei (AGNs), we performed a survey of SiO J = 2-1 (v = 0) transition toward ten gas-rich active galaxies with the IRAM 30 m telescope. As the first survey of SiO in such galaxies, we detected SiO J = 2-1 (v = 0) emission in six galaxies above the 3σ level and one galaxy (NGC 3690) at the 2.7σ level. The detection rate is not related to the AGN type or to star formation activity. In comparison with M82, which is a pure star-forming galaxy without nuclear activity, our SiO detections could not be completely ascribed to being due to star formation activity. This suggests that the AGN feedback may be efficient in producing SiO molecules in such galaxies. Further surveys with large single-dish millimeter telescopes and interferometers are necessary for understanding the origin of SiO in galaxies with nuclear activity.

  20. Galaxy Candidates at z ~ 10 in Archival Data from the Brightest of Reionizing Galaxies (BORG[z8]) Survey

    NASA Astrophysics Data System (ADS)

    Bernard, S. R.; Carrasco, D.; Trenti, M.; Oesch, P. A.; Wu, J. F.; Bradley, L. D.; Schmidt, K. B.; Bouwens, R. J.; Calvi, V.; Mason, C. A.; Stiavelli, M.; Treu, T.

    2016-08-01

    The Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST) enabled the search for the first galaxies observed at z ˜ 8-11 (500-700 Myr after the Big Bang). To continue quantifying the number density of the most luminous galaxies (M AB ˜ -22.0) at the earliest epoch observable with HST, we search for z ˜ 10 galaxies (F125W-dropouts) in archival data from the Brightest of Reionizing Galaxies (BoRG[z8]) survey, originally designed for detection of z ˜ 8 galaxies (F098M-dropouts). By focusing on the deepest 293 arcmin2 of the data along 62 independent lines of sight, we identify six z ˜ 10 candidates satisfying the color selection criteria, detected at S/N > 8 in F160W with M AB = -22.8 to -21.1 if at z = 10. Three of the six sources, including the two brightest, are in a single WFC3 pointing (˜4 arcmin2), suggestive of significant clustering, which is expected from bright galaxies at z ˜ 10. However, the two brightest galaxies are too extended to be likely at z ˜ 10, and one additional source is unresolved and possibly a brown dwarf. The remaining three candidates have m AB ˜ 26, and given the area and completeness of our search, our best estimate is a number density of sources that is marginally higher but consistent at 2σ with searches in legacy fields. Our study highlights that z ˜ 10 searches can yield a small number of candidates, making tailored follow-ups of HST pure-parallel observations viable and effective.

  1. Galaxy Candidates at z ~ 10 in Archival Data from the Brightest of Reionizing Galaxies (BORG[z8]) Survey

    NASA Astrophysics Data System (ADS)

    Bernard, S. R.; Carrasco, D.; Trenti, M.; Oesch, P. A.; Wu, J. F.; Bradley, L. D.; Schmidt, K. B.; Bouwens, R. J.; Calvi, V.; Mason, C. A.; Stiavelli, M.; Treu, T.

    2016-08-01

    The Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST) enabled the search for the first galaxies observed at z ˜ 8–11 (500–700 Myr after the Big Bang). To continue quantifying the number density of the most luminous galaxies (M AB ˜ ‑22.0) at the earliest epoch observable with HST, we search for z ˜ 10 galaxies (F125W-dropouts) in archival data from the Brightest of Reionizing Galaxies (BoRG[z8]) survey, originally designed for detection of z ˜ 8 galaxies (F098M-dropouts). By focusing on the deepest 293 arcmin2 of the data along 62 independent lines of sight, we identify six z ˜ 10 candidates satisfying the color selection criteria, detected at S/N > 8 in F160W with M AB = ‑22.8 to ‑21.1 if at z = 10. Three of the six sources, including the two brightest, are in a single WFC3 pointing (˜4 arcmin2), suggestive of significant clustering, which is expected from bright galaxies at z ˜ 10. However, the two brightest galaxies are too extended to be likely at z ˜ 10, and one additional source is unresolved and possibly a brown dwarf. The remaining three candidates have m AB ˜ 26, and given the area and completeness of our search, our best estimate is a number density of sources that is marginally higher but consistent at 2σ with searches in legacy fields. Our study highlights that z ˜ 10 searches can yield a small number of candidates, making tailored follow-ups of HST pure-parallel observations viable and effective.

  2. survey of the local volume: Isolated southern galaxies

    NASA Astrophysics Data System (ADS)

    Kaisin, S. S.; Kasparova, A. V.; Knyazev, A. Yu.; Karachentsev, I. D.

    2007-05-01

    We present our Hα observations of 11 isolated southern galaxies: SDIG, PGC 51659, E 222-010, E 272-025, E 137-018, IC 4662, Sag DIG, IC 5052, IC 5152, UGCA 438, and E 149-003, with distances from 1 to 7 Mpc. We have determined the total Hα fluxes from these galaxies. The star formation rates in these galaxies range from 10-1 (IC 4662) to 10-4 M ⊙ yr-1 (SDIG) and the gas depletion time at the observed star formation rates lies within the range from 1/6 to 24 Hubble times H 0 -1 .

  3. Hα star formation rates of z > 1 galaxy clusters in the IRAC shallow cluster survey

    SciTech Connect

    Zeimann, Gregory R.; Stanford, S. A.; Brodwin, Mark; Gonzalez, Anthony H.; Mancone, Conor; Snyder, Gregory F.; Stern, Daniel; Eisenhardt, Peter; Dey, Arjun; Moustakas, John

    2013-12-20

    We present Hubble Space Telescope near-IR spectroscopy for 18 galaxy clusters at 1.0 Survey. We use Wide Field Camera 3 grism data to spectroscopically identify Hα emitters in both the cores of galaxy clusters as well as in field galaxies. We find a large cluster-to-cluster scatter in the star formation rates within a projected radius of 500 kpc, and many of our clusters (∼60%) have significant levels of star formation within a projected radius of 200 kpc. A stacking analysis reveals that dust reddening in these star-forming galaxies is positively correlated with stellar mass and may be higher in the field than the cluster at a fixed stellar mass. This may indicate a lower amount of gas in star-forming cluster galaxies than in the field population. Also, Hα equivalent widths of star-forming galaxies in the cluster environment are still suppressed below the level of the field. This suppression is most significant for lower mass galaxies (log M {sub *} < 10.0 M {sub ☉}). We therefore conclude that environmental effects are still important at 1.0 galaxies in galaxy clusters with log M {sub *} ≲ 10.0 M {sub ☉}.

  4. Surveying Galaxy Evolution in the Far-Infrared: A Far-Infrared All-Sky Survey Concept

    NASA Technical Reports Server (NTRS)

    Benford, D. J.; Amato, M. J.; Dwek, E.; Freund, M. M.; Gardner, J. P.; Kashlinsky, A.; Leisawitz, D. T.; Mather, J. C.; Moseley, S. H.; Shafer, R. A.

    2004-01-01

    Half of the total luminosity in the Universe is emitted at rest wavelengths approximately 80-100 microns. At the highest known galaxy redshifts (z greater than or equal to 6) this energy is redshifted to approximately 600 microns. Quantifying the evolution of galaxies at these wavelengths is crucial to our understanding of the formation of structure in the Universe following the big bang. Surveying the whole sky will find the rare and unique objects, enabling follow-up observations. SIRCE, the Survey of Infrared Cosmic Evolution, is such a mission concept under study at NASA's Goddard Space Flight Center. A helium-cooled telescope with ultrasensitive detectors can image the whole sky to the confusion limit in 6 months. Multiple wavelength bands permit the extraction of photometric redshifts, while a large telescope yields a low confusion limit. We discuss the implications of such a survey for galaxy formation and evolution, large-scale structure, star formation, and the structure of interstellar dust.

  5. The Hα Galaxy survey. V. The star formation history of late-type galaxies

    NASA Astrophysics Data System (ADS)

    James, P. A.; Prescott, M.; Baldry, I. K.

    2008-06-01

    Aims: This study of 117 low-redshift Im and Sm galaxies investigates the star formation rates of late-type galaxies, to determine whether they are quasi-continuous or dominated by bursts with quiescent interludes. Methods: We analyse the distribution of star formation timescales (stellar masses/star formation rates) for the entire sample, and of gas depletion timescales for those galaxies with gas mass measurements. Results: We find that, on average, the late-type galaxies studied could have produced their total stellar masses by an extrapolation of their current star formation activity over a period of just under a Hubble time. This is not the case for a comparison sample of earlier-type galaxies, even those with disk-dominated morphologies and similar total stellar masses to the late-type galaxies. The earlier-type galaxies are on average forming their stars more slowly at present than the average rate over their past histories. No totally quiescent Im or Sm galaxies are found, and although some evidence of intrinsic variation in the star formation rate with time is found, this is typically less than a factor of 2 increase or decrease relative to the mean level. The Im and Sm galaxies have extensive gas reservoirs and can maintain star formation at the current rate for more than another Hubble time. The average spatial distribution of star formation in the Im galaxies, and to a lesser extent the Sm galaxies, is very similar to that of the older stellar population traced by the red light. Conclusions: Late type, bulge-free galaxies have a predominantly continuous mode of star formation, and could have assembled their stellar masses through continued star formation over a Hubble time with the currently-observed rate and spatial distribution. There is little evidence in this sample of predominantly isolated field galaxies of significant star formation through brief but intense starburst phases. Based on observations made with the Jacobus Kapteyn Telescope operated

  6. On the recovery of the local group motion from galaxy redshift surveys

    SciTech Connect

    Nusser, Adi; Davis, Marc; Branchini, Enzo E-mail: mdavis@berkeley.edu

    2014-06-20

    There is an ∼150 km s{sup –1} discrepancy between the measured motion of the Local Group (LG) of galaxies with respect to the cosmic microwave background and the linear theory prediction based on the gravitational force field of the large-scale structure in full-sky redshift surveys. We perform a variety of tests which show that the LG motion cannot be recovered to better than 150-200 km s{sup –1} in amplitude and within ≈10° in direction. The tests rely on catalogs of mock galaxies identified in the Millennium simulation using semi-analytic galaxy formation models. We compare these results to the K{sub s} = 11.75 Two-Mass Galaxy Redshift Survey, which provides the deepest and most complete all-sky spatial distribution of galaxies with spectroscopic redshifts available thus far. In our analysis, we use a new concise relation for deriving the LG motion and bulk flow from the true distribution of galaxies in redshift space. Our results show that the main source of uncertainty is the small effective depth of surveys like the Two-Mass Redshift Survey (2MRS), which prevents a proper sampling of the large-scale structure beyond ∼100 h {sup –1} Mpc. Deeper redshift surveys are needed to reach the 'convergence scale' of ≈250 h {sup –1} Mpc in a ΛCDM universe. Deeper surveys would also mitigate the impact of the 'Kaiser rocket' which, in a survey like 2MRS, remains a significant source of uncertainty. Thanks to the quiet and moderate density environment of the LG, purely dynamical uncertainties of the linear predictions are subdominant at the level of ∼90 km s{sup –1}. Finally, we show that deviations from linear galaxy biasing and shot noise errors provide a minor contribution to the total error budget.

  7. Hα imaging survey of Wolf-Rayet galaxies: morphologies and star formation rates

    NASA Astrophysics Data System (ADS)

    Jaiswal, S.; Omar, A.

    2016-10-01

    The Hα and optical broad-band images of 25 nearby Wolf-Rayet (WR) galaxies are presented. The WR galaxies are known to have a recent (≤10 Myr) and massive star formation episode. The photometric Hα fluxes are estimated and corrected for extinction and line contamination in the filter pass-bands. The star formation rates (SFRs) are estimated using Hα images and from archival data in the far-ultraviolet (FUV), far-infrared (FIR) and 1.4-GHz radio continuum wavebands. A comparison of SFRs estimated from different wavebands is made after including similar data available in the literature for other WR galaxies. The Hα-based SFRs are found to be tightly correlated with SFRs estimated from the FUV data. The correlations also exist with SFR estimates based on the radio and FIR data. The WR galaxies also follow the radio-FIR correlation known for normal star-forming galaxies, although it is seen here that the majority of dwarf WR galaxies have a radio deficiency. An analysis using the ratio of non-thermal to thermal radio continuum and the ratio of the FUV to Hα SFRs indicates that WR galaxies have lower non-thermal radio emission compared to normal galaxies, most likely due to a lack of supernovae in the very young star formation episode in the WR galaxies. The morphologies of 16 galaxies in our sample are highly suggestive of an ongoing tidal interaction or a past merger in these galaxies. This survey strengthens the conclusions obtained from previous similar studies indicating the importance of tidal interactions in triggering star-formation in WR galaxies.

  8. AUTOMATIC UNSUPERVISED CLASSIFICATION OF ALL SLOAN DIGITAL SKY SURVEY DATA RELEASE 7 GALAXY SPECTRA

    SciTech Connect

    Almeida, J. Sanchez; Aguerri, J. A. L.; Munoz-Tunon, C.; De Vicente, A. E-mail: jalfonso@iac.e E-mail: angelv@iac.e

    2010-05-01

    Using the k-means cluster analysis algorithm, we carry out an unsupervised classification of all galaxy spectra in the seventh and final Sloan Digital Sky Survey data release (SDSS/DR7). Except for the shift to rest-frame wavelengths and the normalization to the g-band flux, no manipulation is applied to the original spectra. The algorithm guarantees that galaxies with similar spectra belong to the same class. We find that 99% of the galaxies can be assigned to only 17 major classes, with 11 additional minor classes including the remaining 1%. The classification is not unique since many galaxies appear in between classes; however, our rendering of the algorithm overcomes this weakness with a tool to identify borderline galaxies. Each class is characterized by a template spectrum, which is the average of all the spectra of the galaxies in the class. These low-noise template spectra vary smoothly and continuously along a sequence labeled from 0 to 27, from the reddest class to the bluest class. Our Automatic Spectroscopic K-means-based (ASK) classification separates galaxies in colors, with classes characteristic of the red sequence, the blue cloud, as well as the green valley. When red sequence galaxies and green valley galaxies present emission lines, they are characteristic of active galactic nucleus activity. Blue galaxy classes have emission lines corresponding to star formation regions. We find the expected correlation between spectroscopic class and Hubble type, but this relationship exhibits a high intrinsic scatter. Several potential uses of the ASK classification are identified and sketched, including fast determination of physical properties by interpolation, classes as templates in redshift determinations, and target selection in follow-up works (we find classes of Seyfert galaxies, green valley galaxies, as well as a significant number of outliers). The ASK classification is publicly accessible through various Web sites.

  9. CALIFA: a diameter-selected sample for an integral field spectroscopy galaxy survey

    NASA Astrophysics Data System (ADS)

    Walcher, C. J.; Wisotzki, L.; Bekeraité, S.; Husemann, B.; Iglesias-Páramo, J.; Backsmann, N.; Barrera Ballesteros, J.; Catalán-Torrecilla, C.; Cortijo, C.; del Olmo, A.; Garcia Lorenzo, B.; Falcón-Barroso, J.; Jilkova, L.; Kalinova, V.; Mast, D.; Marino, R. A.; Méndez-Abreu, J.; Pasquali, A.; Sánchez, S. F.; Trager, S.; Zibetti, S.; Aguerri, J. A. L.; Alves, J.; Bland-Hawthorn, J.; Boselli, A.; Castillo Morales, A.; Cid Fernandes, R.; Flores, H.; Galbany, L.; Gallazzi, A.; García-Benito, R.; Gil de Paz, A.; González-Delgado, R. M.; Jahnke, K.; Jungwiert, B.; Kehrig, C.; Lyubenova, M.; Márquez Perez, I.; Masegosa, J.; Monreal Ibero, A.; Pérez, E.; Quirrenbach, A.; Rosales-Ortega, F. F.; Roth, M. M.; Sanchez-Blazquez, P.; Spekkens, K.; Tundo, E.; van de Ven, G.; Verheijen, M. A. W.; Vilchez, J. V.; Ziegler, B.

    2014-09-01

    We describe and discuss the selection procedure and statistical properties of the galaxy sample used by the Calar Alto Legacy Integral Field Area (CALIFA) survey, a public legacy survey of 600 galaxies using integral field spectroscopy. The CALIFA "mother sample" was selected from the Sloan Digital Sky Survey (SDSS) DR7 photometric catalogue to include all galaxies with an r-band isophotal major axis between 45'' and 79.2'' and with a redshift 0.005 < z < 0.03. The mother sample contains 939 objects, 600 of which will be observed in the course of the CALIFA survey. The selection of targets for observations is based solely on visibility and thus keeps the statistical properties of the mother sample. By comparison with a large set of SDSS galaxies, we find that the CALIFA sample is representative of galaxies over a luminosity range of -19 > Mr > -23.1 and over a stellar mass range between 109.7 and 1011.4 M⊙. In particular, within these ranges, the diameter selection does not lead to any significant bias against - or in favour of - intrinsically large or small galaxies. Only below luminosities of Mr = -19 (or stellar masses <109.7 M⊙) is there a prevalence of galaxies with larger isophotal sizes, especially of nearly edge-on late-type galaxies, but such galaxies form <10% of the full sample. We estimate volume-corrected distribution functions in luminosities and sizes and show that these are statistically fully compatible with estimates from the full SDSS when accounting for large-scale structure. For full characterization of the sample, we also present a number of value-added quantities determined for the galaxies in the CALIFA sample. These include consistent multi-band photometry based on growth curve analyses; stellar masses; distances and quantities derived from these; morphological classifications; and an overview of available multi-wavelength photometric measurements. We also explore different ways of characterizing the environments of CALIFA galaxies

  10. Early Type Galaxies and Structural Parameters from ESO Public Survey KiDS

    NASA Astrophysics Data System (ADS)

    Roy, N.; Napolitano, N. R.; La Barbera, F.; Tortora, C.; Getman, F.; Radovich, M.; Capaccioli, M.

    The Kilo Degree survey (KiDS) is a large-scale optical imaging survey carried out with the VLT Survey Telescope (VST), which is the ideal tool for galaxy evolution studies. We expect to observe millions of galaxies for which we extract the structural parameters in four wavebands (u, g, r and i). This sample will represent the largest dataset with measured structural parameters up to a redshift z = 0. 5. In this paper we will introduce the sample, and describe the 2D fitting procedure using the 2DPHOT environment and the validation of the parameters with an external catalog.

  11. Galaxy And Mass Assembly (GAMA): end of survey report and data release 2

    NASA Astrophysics Data System (ADS)

    Liske, J.; Baldry, I. K.; Driver, S. P.; Tuffs, R. J.; Alpaslan, M.; Andrae, E.; Brough, S.; Cluver, M. E.; Grootes, M. W.; Gunawardhana, M. L. P.; Kelvin, L. S.; Loveday, J.; Robotham, A. S. G.; Taylor, E. N.; Bamford, S. P.; Bland-Hawthorn, J.; Brown, M. J. I.; Drinkwater, M. J.; Hopkins, A. M.; Meyer, M. J.; Norberg, P.; Peacock, J. A.; Agius, N. K.; Andrews, S. K.; Bauer, A. E.; Ching, J. H. Y.; Colless, M.; Conselice, C. J.; Croom, S. M.; Davies, L. J. M.; De Propris, R.; Dunne, L.; Eardley, E. M.; Ellis, S.; Foster, C.; Frenk, C. S.; Häußler, B.; Holwerda, B. W.; Howlett, C.; Ibarra, H.; Jarvis, M. J.; Jones, D. H.; Kafle, P. R.; Lacey, C. G.; Lange, R.; Lara-López, M. A.; López-Sánchez, Á. R.; Maddox, S.; Madore, B. F.; McNaught-Roberts, T.; Moffett, A. J.; Nichol, R. C.; Owers, M. S.; Palamara, D.; Penny, S. J.; Phillipps, S.; Pimbblet, K. A.; Popescu, C. C.; Prescott, M.; Proctor, R.; Sadler, E. M.; Sansom, A. E.; Seibert, M.; Sharp, R.; Sutherland, W.; Vázquez-Mata, J. A.; van Kampen, E.; Wilkins, S. M.; Williams, R.; Wright, A. H.

    2015-09-01

    The Galaxy And Mass Assembly (GAMA) survey is one of the largest contemporary spectroscopic surveys of low redshift galaxies. Covering an area of ˜286 deg2 (split among five survey regions) down to a limiting magnitude of r < 19.8 mag, we have collected spectra and reliable redshifts for 238 000 objects using the AAOmega spectrograph on the Anglo-Australian Telescope. In addition, we have assembled imaging data from a number of independent surveys in order to generate photometry spanning the wavelength range 1 nm-1 m. Here, we report on the recently completed spectroscopic survey and present a series of diagnostics to assess its final state and the quality of the redshift data. We also describe a number of survey aspects and procedures, or updates thereof, including changes to the input catalogue, redshifting and re-redshifting, and the derivation of ultraviolet, optical and near-infrared photometry. Finally, we present the second public release of GAMA data. In this release, we provide input catalogue and targeting information, spectra, redshifts, ultraviolet, optical and near-infrared photometry, single-component Sérsic fits, stellar masses, Hα-derived star formation rates, environment information, and group properties for all galaxies with r < 19.0 mag in two of our survey regions, and for all galaxies with r < 19.4 mag in a third region (72 225 objects in total). The data base serving these data is available at http://www.gama-survey.org/.

  12. A deep redshift survey of IRAS galaxies towards the Bootes void

    NASA Technical Reports Server (NTRS)

    Dey, Arjun; Strauss, Michael A.; Huchra, John

    1990-01-01

    Redshifts were measured for a complete sample of galaxies detected by the IRAS within 11.5 deg of the center of the void in Bootes discovered by Kirshner et al (1981). There are 12 IRAS galaxies within the void as defined by the above authors, seven of which were discovered in this survey. One of these has a companion at the same redshift. The resulting density of IRAS galaxies in the void is measured to be between 1/6 and 1/3 of the average density; the uncertainty is dominated by Poisson statistics. Good agreement is found between the selection function and number density derived from the present sample and those derived from the all-sky sample of Strauss (1989). The optical spectra of the newly found galaxies in the void are typical of IRAS galaxies in the field.

  13. A Submillimeter Survey of Dust Continuum Emission in Local Dust-Obscured Galaxies

    NASA Astrophysics Data System (ADS)

    Lee, Jong Chul; Hwang, Ho Seong; Lee, Gwang-Ho

    2015-08-01

    Dusty star-forming galaxies are responsible for the bulk of cosmic star formation at 1galaxies is far from clear because of their extreme distances. The study of their local analogs helps us to improve understanding of the drivers of the intense star formation activity at high redshift. The submillimeter data on the 'Rayleigh-Jeans' side of the infrared spectral energy distributions (SEDs) of these galaxies are crucial for deriving the physical parameters of the dust content. We therefore conduct a submillimeter survey of local dust-obscured galaxies (DOGs) with the Caltech Submillimeter Observatory and the Submillimeter Array to study their dust properties. We determine the dust masses and temperatures for 16 local DOGs from the SED fit, and compare them with other dusty galaxies to understand a possible evolutionary link among them.

  14. The NEWFIRM HETDEX Survey - Studying Galaxy Growth with 400,000 Galaxies at 2 < z < 3.5

    NASA Astrophysics Data System (ADS)

    Stevans, Matthew L.; Finkelstein, S. L.; Gebhardt, K.; Jogee, S.; Papovich, C. J.; Ciardullo, R.; Gronwall, C.; Acquaviva, V.; Weinzirl, T.; HETDEX

    2014-01-01

    We present the NEWFIRM HETDEX survey - a K-band survey with NEWFIRM on the KPNO 4m Mayall telescope of a 28 deg^2 region of the Hobby Eberly Telescope Dark Energy Experiment (HETDEX) equatorial field. Here we provide the survey plan, as well as results from the first year (out of four) of our survey. When combined with deep ugriz images from the Dark Energy Camera, deep 3.6 and 4.5 micron images from Spitzer/IRAC, deep far-IR imaging at 250, 350, and 500 microns from HERSCHEL-SPIRE, and R ~ 800 integral-field spectroscopy from the Hobby-Eberly Telescope's VIRUS spectrographs (filling factor 1:1), our observations will allow extinction-corrected star-formation rates (SFRs) to be obtained for ~400,000 galaxies at 2 < z < 3.5. Our survey covers a co-moving volume of 0.5 Gpc^3 and is sensitive to SFRs down to 10 Msol/yr, covering a 10-100 times larger volume and going three times deeper than previous surveys. Our very large volume will allow us to explore galaxy growth as a function of stellar mass, halo mass, and local environment, in addition to providing K-band legacy data for the field.

  15. Self-consistent dynamical models for early-type galaxies in the CALIFA Survey

    NASA Astrophysics Data System (ADS)

    Posti, L.; van de Ven, G.; Binney, J.; Nipoti, C.; Ciotti, L.

    2016-06-01

    We present the first application of self-consistent, continuous models with distribution functions (DFs) depending on the action integrals, to a sample of nearby early-type galaxies in the CALIFA Survey. Each model is axisymmetric, flattened, anisotropic and rotating and the total gravitational potential is self-consistently generated by the density distribution. The spatially-resolved kinematics of the CALIFA Survey gives solid constraints to the models' parameters: we fit the galaxies' surface brightness and the galaxies' spatially resolved kinematics and we estimate dynamical masses in agreement with other dynamical modelling approaches. For each galaxy, the best model provides an analytic DF which fully characterizes the velocity distribution of the stars. The fact that the DF depends on the action integrals makes it easy to extend the present models to have multiple components, such as bulge, stellar disc and dark and stellar halo, in equilibrium with their self-consistent gravitational potential.

  16. Galaxy Evolution Insights from Spectral Modeling of Large Data Sets from the Sloan Digital Sky Survey

    SciTech Connect

    Hoversten, Erik A.

    2007-10-01

    This thesis centers on the use of spectral modeling techniques on data from the Sloan Digital Sky Survey (SDSS) to gain new insights into current questions in galaxy evolution. The SDSS provides a large, uniform, high quality data set which can be exploited in a number of ways. One avenue pursued here is to use the large sample size to measure precisely the mean properties of galaxies of increasingly narrow parameter ranges. The other route taken is to look for rare objects which open up for exploration new areas in galaxy parameter space. The crux of this thesis is revisiting the classical Kennicutt method for inferring the stellar initial mass function (IMF) from the integrated light properties of galaxies. A large data set (~ 105 galaxies) from the SDSS DR4 is combined with more in-depth modeling and quantitative statistical analysis to search for systematic IMF variations as a function of galaxy luminosity. Galaxy Hα equivalent widths are compared to a broadband color index to constrain the IMF. It is found that for the sample as a whole the best fitting IMF power law slope above 0.5 M is Γ = 1.5 ± 0.1 with the error dominated by systematics. Galaxies brighter than around Mr,0.1 = -20 (including galaxies like the Milky Way which has Mr,0.1 ~ -21) are well fit by a universal Γ ~ 1.4 IMF, similar to the classical Salpeter slope, and smooth, exponential star formation histories (SFH). Fainter galaxies prefer steeper IMFs and the quality of the fits reveal that for these galaxies a universal IMF with smooth SFHs is actually a poor assumption. Related projects are also pursued. A targeted photometric search is conducted for strongly lensed Lyman break galaxies (LBG) similar to MS1512-cB58. The evolution of the photometric selection technique is described as are the results of spectroscopic follow-up of the best targets. The serendipitous discovery of two interesting blue compact dwarf galaxies is reported. These

  17. The Mass-Size Relation of Quenched, Quiescent Galaxies in the WISP Survey

    NASA Astrophysics Data System (ADS)

    Pahl, Anthony; Scarlata, Claudia; Rutkowski, Michael J.; Zanella, Anita; Bagley, Micaela B.; Colbert, James W.; Baronchelli, Ivano; Henry, Alaina L.; Hathi, Nimish P.; Teplitz, Harry I.; Rafelski, Marc; Dai, Yu Sophia; Malkan, Matthew Arnold; Mehta, Vihang; Beck, Melanie

    2016-01-01

    The relation between the stellar mass and size, if measured for galaxies of similar types, can be a useful tool for studying galactic evolution. We study the mass-size relation of quenched, quiescent galaxies to determine the effect of star-formation history on the growth of these objects over time. The WFC3 Infrared Spectroscopic Parallels (WISP) survey is a large HST IR grism survey of over 385 fields of ~4 arcmin2 each, and it is ideal for studying the star-formation rate with its broad spectral coverage. Using a subset of these fields with deep IR data and measurements across both filters (28 fields), we perform a color selection and identify 83 quenched galaxies with a median z~1.6. With GALFIT, we measure their effective radius and sersic index on the 2-D surface brightness distribution in the F110W band. We perform fitting of grism spectra of the observed galaxies to derive redshift, stellar mass and age for all galaxies. We combine the size, stellar mass, and stellar age determinations to investigate whether the evolution of the mass-size relation over time is primarily driven by the entrance of newly quenched galaxies or by processes affecting the individual quenched galaxies.

  18. A Wide-Field Survey of the Clustering of Faint Galaxies

    NASA Astrophysics Data System (ADS)

    Woods, David; Fahlman, Gregory G.; Richer, Harvey B.

    The observed clustering of galaxies at intermediate redshifts (z ~0.5-1) is a very useful diagnostic for testing galaxy evolution models. Previous studies of the angular correlation function (omega(theta)) at faint limits (I ~24) have suffered from a lack of precision due to samples containing only ~2-3 thousand galaxies. The introduction of wide-field mosaic cameras, such as the UH8k and CFH12k at CFHT, will significantly enlarge faint galaxy samples and thereby improve estimates of omega(theta). We are currently pursuing a galaxy clustering study in V and I with a survey area ~6 times larger (~0.2 sq. deg.) than our previous work (Woods and Fahlman 1997), using data obtained with the UH8k. Our analysis of the ~7000 galaxies contained in this data set will act as a pilot study leading towards the acquisition of deeper and larger samples of galaxies, to be obtained in the near future with mosaic cameras (this already being done to brighter limits by Postman et al. 1998). A preliminary analysis of a portion of the data is presented and the benefits of the upcoming, larger 2-d photometric surveys are summarized.

  19. Byurakan-IRAS galaxies: a survey for FIR flux limited objects

    NASA Astrophysics Data System (ADS)

    Mickaelian, A. M.

    2003-07-01

    A program of optical identifications of all IRAS sources in a large area (|b|>15° and ℓ>+61°) on the basis of the First Byurakan Survey (FBS) low-dispersion spectra is aimed at revealing all FIR flux limited (0.6 Jy at 60μm, and 1.0 Jy at 100μm, i. e. the IRAS PSC completeness limit) objects and study its contents. 1577 previously unidentified IRAS point sources have been optically identified in an area with 1487 deg2, of which 1178 are galaxies, and 399 are stars. The identifications program brought to 2 samples of objects: BIS (Byurakan-IRAS Stars), and BIG (Byurakan-IRAS Galaxies). A redshift survey for BIG objects have been undertaken with 3 telescopes (Byurakan 2.6m, Russian SAO 6m, and Haute-Provence 1.93m): 213 galaxies have been observed so far, and their redshifts and activity types are available. The BIG objects contain Seyferts, LINERs, composite spectrum AGNs, high-luminosity IR galaxies, groups of galaxies, interacting and merging galaxies, as well as obscured IRAS galaxies. The redshifts are in the range 0.008-0.173, and the obtained FIR is in the range 3x10^9

  20. The VIMOS Public Extragalactic Redshift Survey. Reconstruction of the redshift-space galaxy density field&

    NASA Astrophysics Data System (ADS)

    Granett, B. R.; Branchini, E.; Guzzo, L.; Abbas, U.; Adami, C.; Arnouts, S.; Bel, J.; Bolzonella, M.; Bottini, D.; Cappi, A.; Coupon, J.; Cucciati, O.; Davidzon, I.; De Lucia, G.; de la Torre, S.; Fritz, A.; Franzetti, P.; Fumana, M.; Garilli, B.; Ilbert, O.; Iovino, A.; Krywult, J.; Le Brun, V.; Le Fèvre, O.; Maccagni, D.; Małek, K.; Marulli, F.; McCracken, H. J.; Polletta, M.; Pollo, A.; Scodeggio, M.; Tasca, L. A. M.; Tojeiro, R.; Vergani, D.; Zanichelli, A.; Burden, A.; Di Porto, C.; Marchetti, A.; Marinoni, C.; Mellier, Y.; Moutard, T.; Moscardini, L.; Nichol, R. C.; Peacock, J. A.; Percival, W. J.; Zamorani, G.

    2015-11-01

    Aims: Using the VIMOS Public Extragalactic Redshift Survey (VIPERS) we aim to jointly estimate the keyparameters that describe the galaxy density field and its spatial correlations in redshift space. Methods: We use the Bayesian formalism to jointly reconstruct the redshift-space galaxy density field, power spectrum, galaxy bias and galaxy luminosity function given the observations and survey selection function. The high-dimensional posterior distribution is explored using the Wiener filter within a Gibbs sampler. We validate the analysis using simulated catalogues and apply it to VIPERS data taking into consideration the inhomogeneous selection function. Results: We present joint constraints on the anisotropic power spectrum, and the bias and number density of red and blue galaxy classes in luminosity and redshift bins as well as the measurement covariances of these quantities. We find that the inferred galaxy bias and number density parameters are strongly correlated although they are only weakly correlated with the galaxy power spectrum. The power spectrum and redshift-space distortion parameters are in agreement with previous VIPERS results with the value of the growth rate fσ8 = 0.38 with 18% uncertainty at redshift 0.7. Appendices are available in electronic form at http://www.aanda.org

  1. Chemo-Kinematic Survey of z ~ 1 Star Forming Galaxies using Keck OSIRIS LGS-AO

    NASA Astrophysics Data System (ADS)

    Mieda, Etsuko; Wright, Shelley A.; Larkin, James E.; Armus, Lee; Juneau, Stephanie

    2015-02-01

    We present first results from the Intermediate Redshift OSIRIS Chemo-Kinematic Survey (IROCKS) of z ~ 1 star forming galaxies (Mieda et al. in prep). We have targeted Hα and [NII] emission lines in J-band and have spatially resolved the galaxies at sub-kilo parsec scale. We have combined our sample with deep HST continuum images, and are able to reveal the dynamics, morphologies, metallicity distribution, emission-line diagnostics, and star formation rates of galaxies spanning this crucial z ~ 1 epoch.

  2. The HST Snapshot Survey of Nearby Dwarf Galaxy Candidates. III. Resolved Dwarf Galaxies In and Beyond the Local Group

    NASA Astrophysics Data System (ADS)

    Grebel, E. K.; Seitzer, P.; Dolphin, A. E.; Geisler, D.; Guhathakurta, P.; Hodge, P. W.; Karachentsev, I. D.; Karachentseva, V. E.; Sarajedini, A.; Sharina, M. E.

    1999-12-01

    We present results for several nearby, resolved dwarf galaxies imaged with WFPC2 in the framework of our HST snapshot survey of nearby dwarf galaxy candidates (Seitzer et al., paper I in this series). All data presented here were analyzed with the automated photometry package HSTPHOT (Dolphin et al., paper IV in this series). Our closest target is the recently discovered Cassiopeia dwarf spheroidal (dSph) galaxy (Karachentsev & Karachentseva 1999, A&A, 341, 355), a new Local Group member and companion of M31 (Grebel & Guhathakurta 1999, ApJ, 511, 101). Our WFPC2 snapshot data reveal a pronounced red horizontal branch in Cas dSph. IC 5152 is a dwarf irregular (dIrr) just beyond the Local Group. Our data show a significant intermediate-age population with a strongly tilted asymptotic giant branch (AGB), a substantial young population, and a wide giant branch. Other nearby galaxies to be discussed include NGC 1560, ESO 471-G006, ESO 470-G018, and KK 035. Most of these galaxies are being resolved into stars for the first time. We describe their properties in detail and derive distances for all dwarfs with a well-defined tip of the red giant branch. Membership of these galaxies in nearby groups is discussed. Support for this work was provided by NASA through grant GO-08192.97A from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. EKG acknowledges support by NASA through grant HF-01108.01-98A from the Space Telescope Science Institute. EKG and IDK are supported by the Henri Chrétien International Research Grant administered by the American Astronomical Society. PG is an Alfred P. Sloan Research Fellow.

  3. A survey of the properties of early-type galaxies

    NASA Technical Reports Server (NTRS)

    Bregman, Joel N.; Roberts, M. S.; Hogg, D. E.

    1990-01-01

    A compilation of the properties of elliptical and early disk galaxies was completed. In addition to material from the literature, such as Infrared Astronomy Satellite (IRAS) fluxes, the compilation includes recent measurements of HI and CO, as well as a review of the x ray properties by Forman and Jones. The data are used to evaluate the gas content of early systems and to search for correlations with x ray emission. The interstellar medium in early-type galaxies is generally dominated by hot interstellar gas (T approx. 10 to the 7th power K; c.f. the review by Fabbiano 1989 and references therein). In addition, a significant fraction of these galaxies show infrared emission (Knapp, et al., 1989), optical emission lines, and visible dust. Sensitive studies in HI and CO of a number of these galaxies have been completed recently, resulting in several detections, particularly of the later types. Researchers wish to understand the connection among these different forms of the interstellar medium, and to examine the theoretical picture of the fate of the hot gas. To do so, they compiled observations of several forms of interstellar matter for a well-defined sample of early-type galaxies. Here they present a statistical analysis of this data base and discuss the implications of the results.

  4. THE STAR FORMATION AND NUCLEAR ACCRETION HISTORIES OF NORMAL GALAXIES IN THE AGES SURVEY

    SciTech Connect

    Watson, Casey R.; Kochanek, Christopher S.; Forman, William R.; Hickox, Ryan C.; Jones, Christine J.; Kenter, Almus T.; Murray, Steve S.; Vikhlinin, Alexey; Fazio, Giovani G.; Green, Paul J.; Brown, Michael J. I.; Brand, Kate; Dey, Arjun; Jannuzi, Buell T.; Rieke, Marcia; Eisenstein, Daniel J.; McNamara, Brian R.; Shields, Joseph C.

    2009-05-10

    We combine IR, optical, and X-ray data from the overlapping, 9.3 deg{sup 2} NOAO Deep Wide-Field Survey, AGN and Galaxy Evolution Survey (AGES), and XBooetes Survey to measure the X-ray evolution of 6146 normal galaxies as a function of absolute optical luminosity, redshift, and spectral type over the largely unexplored redshift range 0.1 {approx}< z {approx}< 0.5. Because only the closest or brightest of the galaxies are individually detected in X-rays, we use a stacking analysis to determine the mean properties of the sample. Our results suggest that X-ray emission from spectroscopically late-type galaxies is dominated by star formation, while that from early-type galaxies is dominated by a combination of hot gas and active galactic nucleus (AGN) emission. We find that the mean star formation and supermassive black hole accretion rate densities evolve like {approx}(1 + z){sup 3{+-}}{sup 1}, in agreement with the trends found for samples of bright, individually detectable starburst galaxies and AGN. Our work also corroborates the results of many previous stacking analyses of faint source populations, with improved statistics.

  5. GALAXY CLUSTERS DISCOVERED WITH A SUNYAEV-ZEL'DOVICH EFFECT SURVEY

    SciTech Connect

    Staniszewski, Z.; Ade, P. A. R.; Aird, K. A.; Hrubes, J. D.; Benson, B. A.; Cho, H.-M.; Holzapfel, W. L.; Lee, A. T.; Bleem, L. E.; Carlstrom, J. E.; Chang, C. L.; Crawford, T. M.; Crites, A. T.; Keisler, R.; De Haan, T.; Dobbs, M. A.; Holder, G. P.; Lanting, T. M.; Halverson, N. W.; Joy, M.

    2009-08-10

    The South Pole Telescope (SPT) is conducting a Sunyaev-Zel'dovich (SZ) effect survey over large areas of the southern sky, searching for massive galaxy clusters to high redshift. In this preliminary study, we focus on a 40 deg{sup 2} area targeted by the Blanco Cosmology Survey (BCS), which is centered roughly at right ascension 5{sup h}30{sup m}, declination -53 deg. (J2000). Over two seasons of observations, this entire region has been mapped by the SPT at 95 GHz, 150 GHz, and 225 GHz. We report the four most significant SPT detections of SZ clusters in this field, three of which were previously unknown and, therefore, represent the first galaxy clusters discovered with an SZ survey. The SZ clusters are detected as decrements with greater than 5{sigma} significance in the high-sensitivity 150 GHz SPT map. The SZ spectrum of these sources is confirmed by detections of decrements at the corresponding locations in the 95 GHz SPT map and nondetections at those locations in the 225 GHz SPT map. Multiband optical images from the BCS survey demonstrate significant concentrations of similarly colored galaxies at the positions of the SZ detections. Photometric redshift estimates from the BCS data indicate that two of the clusters lie at moderate redshift (z {approx} 0.4) and two at high redshift (z {approx}> 0.8). One of the SZ detections was previously identified as a galaxy cluster in the optical as part of the Abell supplementary southern cluster catalog and in the X-ray using data from the ROSAT All-Sky Survey (RASS). Potential RASS counterparts (not previously identified as clusters) are also found for two of the new discoveries. These first four galaxy clusters are the most significant SZ detections from a subset of the ongoing SPT survey. As such, they serve as a demonstration that SZ surveys, and the SPT in particular, can be an effective means for finding galaxy clusters.

  6. The Vimos VLT deep survey. Global properties of 20,000 galaxies in the IAB < 22.5 WIDE survey

    NASA Astrophysics Data System (ADS)

    Garilli, B.; Le Fèvre, O.; Guzzo, L.; Maccagni, D.; Le Brun, V.; de la Torre, S.; Meneux, B.; Tresse, L.; Franzetti, P.; Zamorani, G.; Zanichelli, A.; Gregorini, L.; Vergani, D.; Bottini, D.; Scaramella, R.; Scodeggio, M.; Vettolani, G.; Adami, C.; Arnouts, S.; Bardelli, S.; Bolzonella, M.; Cappi, A.; Charlot, S.; Ciliegi, P.; Contini, T.; Foucaud, S.; Gavignaud, I.; Ilbert, O.; Iovino, A.; Lamareille, F.; McCracken, H. J.; Marano, B.; Marinoni, C.; Mazure, A.; Merighi, R.; Paltani, S.; Pellò, R.; Pollo, A.; Pozzetti, L.; Radovich, M.; Zucca, E.; Blaizot, J.; Bongiorno, A.; Cucciati, O.; Mellier, Y.; Moreau, C.; Paioro, L.

    2008-08-01

    The VVDS-Wide survey has been designed to trace the large-scale distribution of galaxies at z ~ 1 on comoving scales reaching ~100~h-1 Mpc, while providing a good control of cosmic variance over areas as large as a few square degrees. This is achieved by measuring redshifts with VIMOS at the ESO VLT to a limiting magnitude IAB = 22.5, targeting four independent fields with sizes of up to 4 deg2 each. We discuss the survey strategy which covers 8.6 deg2 and present the general properties of the current redshift sample. This includes 32 734 spectra in the four regions, covering a total area of 6.1 deg2 with a sampling rate of 22 to 24%. This paper accompanies the public release of the first 18 143 redshifts of the VVDS-Wide survey from the 4 deg2 contiguous area of the F22 field at RA = 22^h. We have devised and tested an objective method to assess the quality of each spectrum, providing a compact figure-of-merit. This is particularly effective in the case of long-lasting spectroscopic surveys with varying observing conditions. Our figure of merit is a measure of the robustness of the redshift measurement and, most importantly, can be used to select galaxies with uniform high-quality spectra to carry out reliable measurements of spectral features. We also use the data available over the four independent regions to directly measure the variance in galaxy counts. We compare it with general predictions from the observed galaxy two-point correlation function at different redshifts and with that measured in mock galaxy surveys built from the Millennium simulation. The purely magnitude-limited VVDS Wide sample includes 19 977 galaxies, 304 type I AGNs, and 9913 stars. The redshift success rate is above 90% independent of magnitude. A cone diagram of the galaxy spatial distribution provides us with the current largest overview of large-scale structure up to z ~ 1, showing a rich texture of over- and under-dense regions. We give the mean N(z) distribution averaged over 6

  7. SHELS: A complete galaxy redshift survey with R ≤ 20.6

    SciTech Connect

    Geller, Margaret J.; Hwang, Ho Seong; Fabricant, Daniel G.; Kurtz, Michael J.; Dell'Antonio, Ian P.; Zahid, Harus Jabran E-mail: hhwang@cfa.harvard.edu E-mail: mkurtz@cfa.harvard.edu E-mail: jabran@ifa.hawaii.edu

    2014-08-01

    The SHELS (Smithsonian Hectospec Lensing Survey) is a complete redshift survey covering two well-separated fields (F1 and F2) of the Deep Lens Survey to a limiting R = 20.6. Here we describe the redshift survey of the F2 field (R.A.{sub 2000} = 09{sup h}19{sup m}32.4 and decl.{sub 2000} = +30°00'00''). The survey includes 16,294 new redshifts measured with the Hectospec on the MMT. The resulting survey of the 4 deg{sup 2} F2 field is 95% complete to R = 20.6, currently the densest survey to this magnitude limit. The median survey redshift is z = 0.3; the survey provides a view of structure in the range 0.1 ≲ z ≲ 0.6. An animation displays the large-scale structure in the survey region. We provide a redshift, spectral index D {sub n}4000, and stellar mass for each galaxy in the survey. We also provide a metallicity for each galaxy in the range 0.2 survey, we examine the behavior of the index D {sub n}4000 as a function of galaxy luminosity, stellar mass, and redshift. The known evolutionary and stellar mass dependent properties of the galaxy population are cleanly evident in the data. We also show that the mass-metallicity relation previously determined from these data is robust to the analysis approach.

  8. The impact from survey depth and resolution on the morphological classification of galaxies

    NASA Astrophysics Data System (ADS)

    Pović, M.; Márquez, I.; Masegosa, J.; Perea, J.; Olmo, A. del; Simpson, C.; Aguerri, J. A. L.; Ascaso, B.; Jiménez-Teja, Y.; López-Sanjuan, C.; Molino, A.; Pérez-García, A. M.; Viironen, K.; Husillos, C.; Cristóbal-Hornillos, D.; Caldwell, C.; Benítez, N.; Alfaro, E.; Aparicio-Villegas, T.; Broadhurst, T.; Cabrera-Caño, J.; Castander, F. J.; Cepa, J.; Cerviño, M.; Fernández-Soto, A.; Delgado, R. M. González; Infante, L.; Martínez, V. J.; Moles, M.; Prada, F.; Quintana, J. M.

    2015-10-01

    We consistently analyse for the first time the impact of survey depth and spatial resolution on the most used morphological parameters for classifying galaxies through non-parametric methods: Abraham and Conselice-Bershady concentration indices, Gini, M20 moment of light, asymmetry, and smoothness. Three different non-local data sets are used, Advanced Large Homogeneous Area Medium Band Redshift Astronomical (ALHAMBRA) and Subaru/XMM-Newton Deep Survey (SXDS, examples of deep ground-based surveys), and Cosmos Evolution Survey (COSMOS, deep space-based survey). We used a sample of 3000 local, visually classified galaxies, measuring their morphological parameters at their real redshifts (z ˜ 0). Then we simulated them to match the redshift and magnitude distributions of galaxies in the non-local surveys. The comparisons of the two sets allow us to put constraints on the use of each parameter for morphological classification and evaluate the effectiveness of the commonly used morphological diagnostic diagrams. All analysed parameters suffer from biases related to spatial resolution and depth, the impact of the former being much stronger. When including asymmetry and smoothness in classification diagrams, the noise effects must be taken into account carefully, especially for ground-based surveys. M20 is significantly affected, changing both the shape and range of its distribution at all brightness levels. We suggest that diagnostic diagrams based on 2-3 parameters should be avoided when classifying galaxies in ground-based surveys, independently of their brightness; for COSMOS they should be avoided for galaxies fainter than F814 = 23.0. These results can be applied directly to surveys similar to ALHAMBRA, SXDS and COSMOS, and also can serve as an upper/lower limit for shallower/deeper ones.

  9. A 1400-MHz survey of 1478 Abell clusters of galaxies

    NASA Technical Reports Server (NTRS)

    Owen, F. N.; White, R. A.; Hilldrup, K. C.; Hanisch, R. J.

    1982-01-01

    Observations of 1478 Abell clusters of galaxies with the NRAO 91-m telescope at 1400 MHz are reported. The measured beam shape was deconvolved from the measured source Gaussian fits in order to estimate the source size and position angle. All detected sources within 0.5 corrected Abell cluster radii are listed, including the cluster number, richness class, distance class, magnitude of the tenth brightest galaxy, redshift estimate, corrected cluster radius in arcmin, right ascension and error, declination and error, total flux density and error, and angular structure for each source.

  10. Redshift-Distance Survey of Early-Type Galaxies. I. Sample Selection, Properties, and Completeness

    NASA Astrophysics Data System (ADS)

    da Costa, L. N.; Bernardi, M.; Alonso, M. V.; Wegner, G.; Willmer, C. N. A.; Pellegrini, P. S.; Rité, C.; Maia, M. A. G.

    2000-07-01

    This is the first in a series of papers describing the recently completed all-sky redshift-distance survey of Early-type NEARby galaxies (ENEAR) carried out for peculiar velocity analysis. The sample is divided into two parts and consists of 1607 elliptical and lenticular galaxies with cz<=7000 km s-1 and with blue magnitudes brighter than mB=14.5 (ENEARm) and of galaxies in clusters (ENEARc). Galaxy distances based on the Dn-σ and fundamental plane (FP) relations are now available for 1359 and 1107 ENEARm galaxies, respectively, with roughly 80% based on new data gathered by our group. The Dn-σ and FP template distance relations are derived by combining 569 and 431 galaxies in 28 clusters, respectively, of which about 60% are based on our new measurements. To date the ENEAR survey has accumulated 2200 R-band images yielding photometric parameters for 1398 galaxies and 2300 spectra yielding 1745 measurements of central velocity dispersions and spectral line indices for 1210 galaxies. In addition, there are some 1834 spectra of early-type galaxies available in the Southern Sky Redshift Survey (SSRS+SSRS2) database, out of which roughly 800 galaxies yield high-quality measurements of velocity dispersions and spectral line indices, bringing the total number of galaxies with available spectral information to about 2000. Combined with measurements publicly available, a catalog has been assembled comprising ~4500 measurements of central velocity dispersions for about 2800 galaxies, ~3700 measurements of photometric parameters for about 2000 galaxies, and distances for about 1900 galaxies. This extensive database provides information on galaxies with multiple observations from different telescope/instrument configurations and from different authors. These overlapping data are used to derive relations to transform all available measurements into a common system, thereby ensuring the homogeneity of the database. The ENEARm redshift-distance survey extends the earlier work

  11. Low/High Redshift Classification of Emission Line Galaxies in the HETDEX survey

    NASA Astrophysics Data System (ADS)

    Acquaviva, Viviana; Gawiser, Eric; Leung, Andrew S.; Martin, Mario R.

    2014-05-01

    We discuss different methods to separate high- from low-redshift galaxies based on a combination of spectroscopic and photometric observations. Our baseline scenario is the Hobby-Eberly Telescope Dark Energy eXperiment (HETDEX) survey, which will observe several hundred thousand Lyman Alpha Emitting (LAE) galaxies at 1.9 < z < 3.5, and for which the main source of contamination is [OII]-emitting galaxies at z < 0.5. Additional information useful for the separation comes from empirical knowledge of LAE and [OII] luminosity functions and equivalent width distributions as a function of redshift. We consider three separation techniques: a simple cut in equivalent width, a Bayesian separation method, and machine learning algorithms, including support vector machines. These methods can be easily applied to other surveys and used on simulated data in the framework of survey planning.

  12. THE MASSIVE DISTANT CLUSTERS OF WISE SURVEY: THE FIRST DISTANT GALAXY CLUSTER DISCOVERED BY WISE

    SciTech Connect

    Gettings, Daniel P.; Gonzalez, Anthony H.; Mancone, Conor; Stanford, S. Adam; Eisenhardt, Peter R. M.; Stern, Daniel; Brodwin, Mark; Zeimann, Gregory R.; Masci, Frank J.; Papovich, Casey; Tanaka, Ichi; Wright, Edward L.

    2012-11-01

    We present spectroscopic confirmation of a z = 0.99 galaxy cluster discovered using data from the Wide-field Infrared Survey Explorer (WISE). This is the first z {approx} 1 cluster candidate from the Massive Distant Clusters of WISE Survey to be confirmed. It was selected as an overdensity of probable z {approx}> 1 sources using a combination of WISE and Sloan Digital Sky Survey DR8 photometric catalogs. Deeper follow-up imaging data from Subaru and WIYN reveal the cluster to be a rich system of galaxies, and multi-object spectroscopic observations from Keck confirm five cluster members at z = 0.99. The detection and confirmation of this cluster represents a first step toward constructing a uniformly selected sample of distant, high-mass galaxy clusters over the full extragalactic sky using WISE data.

  13. The SAMI Galaxy Survey: extraplanar gas, galactic winds and their association with star formation history

    NASA Astrophysics Data System (ADS)

    Ho, I.-Ting; Medling, Anne M.; Bland-Hawthorn, Joss; Groves, Brent; Kewley, Lisa J.; Kobayashi, Chiaki; Dopita, Michael A.; Leslie, Sarah K.; Sharp, Rob; Allen, James T.; Bourne, Nathan; Bryant, Julia J.; Cortese, Luca; Croom, Scott M.; Dunne, Loretta; Fogarty, L. M. R.; Goodwin, Michael; Green, Andy W.; Konstantopoulos, Iraklis S.; Lawrence, Jon S.; Lorente, Nuria P. F.; Owers, Matt S.; Richards, Samuel; Sweet, Sarah M.; Tescari, Edoardo; Valiante, Elisabetta

    2016-04-01

    We investigate a sample of 40 local, main-sequence, edge-on disc galaxies using integral field spectroscopy with the Sydney-AAO Multi-object Integral field spectrograph (SAMI) Galaxy Survey to understand the link between properties of the extraplanar gas and their host galaxies. The kinematics properties of the extraplanar gas, including velocity asymmetries and increased dispersion, are used to differentiate galaxies hosting large-scale galactic winds from those dominated by the extended diffuse ionized gas. We find rather that a spectrum of diffuse gas-dominated to wind-dominated galaxies exist. The wind-dominated galaxies span a wide range of star formation rates (SFRs; -1 ≲ log (SFR/M⊙ yr-1) ≲ 0.5) across the whole stellar mass range of the sample (8.5 ≲ log (M*/M⊙) ≲ 11). The wind galaxies also span a wide range in SFR surface densities (10- 3-10- 1.5 M⊙ yr- 1 kpc- 2) that is much lower than the canonical threshold of 0.1 M⊙ yr- 1 kpc- 2. The wind galaxies on average have higher SFR surface densities and higher HδA values than those without strong wind signatures. The enhanced HδA indicates that bursts of star formation in the recent past are necessary for driving large-scale galactic winds. We demonstrate with Sloan Digital Sky Survey data that galaxies with high SFR surface density have experienced bursts of star formation in the recent past. Our results imply that the galactic winds revealed in our study are indeed driven by bursts of star formation, and thus probing star formation in the time domain is crucial for finding and understanding galactic winds.

  14. Origin of 12 micrometer Emission Across Galaxy Populations from Wise and ADSS Surveys

    NASA Technical Reports Server (NTRS)

    Donso, E.; Yan, Lin; Tsai, C.; Eisenhardt, P; Stern, D.; Assef, R. J.; Leisawitz, D.; Jarrett, T. H.; Stanford, S. A.

    2012-01-01

    We cross-matched Wide-field Infrared Survey Explorer sources brighter than 1 mJy at 12 micron with the Sloan Digital Sky Survey galaxy spectroscopic catalog to produce a sample of approx. 10(exp 5) galaxies at z = 0.08, the largest of its kind. This sample is dominated (70%) by star-forming (SF) galaxies from the blue sequence, with total IR luminosities in the range approx 10(exp 8)-10(exp 12) Solar L. We identify which stellar populations are responsible for most of the 12 micron emission. We find that most (approx 80%) of the 12 micron emission in SF galaxies is produced by stellar populations younger than 0.6 Gyr. In contrast, the 12 micron emission in weak active galactic nuclei (AGNs; L [O iii] < 10(exo 7) solar L ) is produced by older stars, with ages of approx 1-3 Gyr. We find that L(sub 12 micron) linearly correlates with stellar mass for SF galaxies. At fixed 12 micron luminosity, weak AGNs deviate toward higher masses since they tend to be hosted by massive, early-type galaxies with older stellar populations. SF galaxies and weak AGNs follow different L(sub 12 micron) - SFR (star formation rate) relations, with weak AGNs showing excess 12 micron emission at low SFR (0.02-1 solar M /yr). This is likely due to dust grains heated by older stars. While the specific star formation rate (SSFR) of SF galaxies is nearly constant, the SSFR of weak AGNs decreases by approx 3 orders of magnitude, reflecting the very different star formation efficiencies between SF galaxies and massive, early-type galaxies. Stronger type II AGNs in our sample (L(sub [O iii]) > 10(exp 7) solar L ), act as an extension of massive SF galaxies, connecting the SF and weak AGN sequences. This suggests a picture where galaxies form stars normally until an AGN (possibly after a starburst episode) starts to gradually quench the SF activity. We also find that 4.6-12 micron color is a useful first-order indicator of SF activity in a galaxy when no other data are available.

  15. Bayesian redshift-space distortions correction from galaxy redshift surveys

    NASA Astrophysics Data System (ADS)

    Kitaura, Francisco-Shu; Ata, Metin; Angulo, Raul E.; Chuang, Chia-Hsun; Rodríguez-Torres, Sergio; Monteagudo, Carlos Hernández; Prada, Francisco; Yepes, Gustavo

    2016-03-01

    We present a Bayesian reconstruction method which maps a galaxy distribution from redshift- to real-space inferring the distances of the individual galaxies. The method is based on sampling density fields assuming a lognormal prior with a likelihood modelling non-linear stochastic bias. Coherent redshift-space distortions are corrected in a Gibbs-sampling procedure by moving the galaxies from redshift- to real-space according to the peculiar motions derived from the recovered density field using linear theory. The virialized distortions are corrected by sampling candidate real-space positions along the line of sight, which are compatible with the bulk flow corrected redshift-space position adding a random dispersion term in high-density collapsed regions (defined by the eigenvalues of the Hessian). This approach presents an alternative method to estimate the distances to galaxies using the three-dimensional spatial information, and assuming isotropy. Hence the number of applications is very broad. In this work, we show the potential of this method to constrain the growth rate up to k ˜ 0.3 h Mpc-1. Furthermore it could be useful to correct for photometric redshift errors, and to obtain improved baryon acoustic oscillations (BAO) reconstructions.

  16. Adaptive Optics Imaging Survey of Luminous Infrared Galaxies

    SciTech Connect

    Laag, E A; Canalizo, G; van Breugel, W; Gates, E L; de Vries, W; Stanford, S A

    2006-03-13

    We present high resolution imaging observations of a sample of previously unidentified far-infrared galaxies at z < 0.3. The objects were selected by cross-correlating the IRAS Faint Source Catalog with the VLA FIRST catalog and the HST Guide Star Catalog to allow for adaptive optics observations. We found two new ULIGs (with L{sub FIR} {ge} 10{sup 12} L{sub {circle_dot}}) and 19 new LIGs (with L{sub FIR} {ge} 10{sup 11} L{sub {circle_dot}}). Twenty of the galaxies in the sample were imaged with either the Lick or Keck adaptive optics systems in H or K{prime}. Galaxy morphologies were determined using the two dimensional fitting program GALFIT and the residuals examined to look for interesting structure. The morphologies reveal that at least 30% are involved in tidal interactions, with 20% being clear mergers. An additional 50% show signs of possible interaction. Line ratios were used to determine powering mechanism; of the 17 objects in the sample showing clear emission lines--four are active galactic nuclei and seven are starburst galaxies. The rest exhibit a combination of both phenomena.

  17. The 2dF Galaxy Redshift Survey: spectra and redshifts

    NASA Astrophysics Data System (ADS)

    Colless, Matthew; Dalton, Gavin; Maddox, Steve; Sutherland, Will; Norberg, Peder; Cole, Shaun; Bland-Hawthorn, Joss; Bridges, Terry; Cannon, Russell; Collins, Chris; Couch, Warrick; Cross, Nicholas; Deeley, Kathryn; De Propris, Roberto; Driver, Simon P.; Efstathiou, George; Ellis, Richard S.; Frenk, Carlos S.; Glazebrook, Karl; Jackson, Carole; Lahav, Ofer; Lewis, Ian; Lumsden, Stuart; Madgwick, Darren; Peacock, John A.; Peterson, Bruce A.; Price, Ian; Seaborne, Mark; Taylor, Keith

    2001-12-01

    The 2dF Galaxy Redshift Survey (2dFGRS) is designed to measure redshifts for approximately 250000 galaxies. This paper describes the survey design, the spectroscopic observations, the redshift measurements and the survey data base. The 2dFGRS uses the 2dF multifibre spectrograph on the Anglo-Australian Telescope, which is capable of observing 400 objects simultaneously over a 2° diameter field. The source catalogue for the survey is a revised and extended version of the APM galaxy catalogue, and the targets are galaxies with extinction-corrected magnitudes brighter than bJ=19.45. The main survey regions are two declination strips, one in the southern Galactic hemisphere spanning 80°×15° around the SGP, and the other in the northern Galactic hemisphere spanning 75°×10° along the celestial equator; in addition, there are 99 fields spread over the southern Galactic cap. The survey covers 2000deg2 and has a median depth of z=0.11. Adaptive tiling is used to give a highly uniform sampling rate of 93 per cent over the whole survey region. Redshifts are measured from spectra covering 3600-8000Å at a two-pixel resolution of 9.0Å and a median S/N of 13pixel-1. All redshift identifications are visually checked and assigned a quality parameter Q in the range 1-5 Q>=3 redshifts are 98.4 per cent reliable and have an rms uncertainty of 85kms-1. The overall redshift completeness for Q>=3 redshifts is 91.8 per cent, but this varies with magnitude from 99 per cent for the brightest galaxies to 90 per cent for objects at the survey limit. The 2dFGRS data base is available on the World Wide Web at http://www.mso.anu.edu.au/2dFGRS.

  18. THE SPITZER INTERACTING GALAXIES SURVEY: A MID-INFRARED ATLAS OF STAR FORMATION

    SciTech Connect

    Brassington, N. J.; Zezas, A.; Ashby, M. L. N.; Lanz, L.; Smith, Howard A.; Willner, S. P.; Klein, C.

    2015-05-15

    The Spitzer Interacting Galaxies Survey is a sample of 103 nearby galaxies in 48 systems, selected using association likelihoods and therefore free from disturbed morphology biases. All galaxies have been observed with Infrared Array Camera and MIPS 24 μm bands from the Spitzer Space Telescope. This catalog presents the global flux densities and colors of all systems and correlations between the interacting systems and their specific star formation rate (sSFR). This sample contains a wide variety of galaxy interactions with systems ranging in mass, mass ratios, and gas-content as well as interaction strength. This study seeks to identify the process of triggering star formation in galaxy interactions, therefore, we focus on the non-active galactic nucleus spiral galaxies only. From this subset of 70 spiral galaxies we have determined that this sample has enhanced sSFR compared to a sample of non-interacting field galaxies. Through optical data we have classified each system by “interaction strength”; the strongly interacting (Stage 4) galaxies have higher sSFR values than the weakly (Stage 2) and moderately (Stage 3) interacting systems. However, the Stage 2 and 3 systems have statistically identical sSFR properties, despite the lack of optical interaction signatures exhibited by the Stage 2 galaxies. We suggest that the similarity of sSFR in these stages could be a consequence of some of these Stage 2 systems actually being post-perigalactic and having had sufficient time for their tidal features to fade to undetectable levels. This interpretation is consistent with the correlation of sSFR with separation, which we have determined to have little variation up to 100 kpc.

  19. The Spitzer Interacting Galaxies Survey: A Mid-infrared Atlas of Star Formation

    NASA Astrophysics Data System (ADS)

    Brassington, N. J.; Zezas, A.; Ashby, M. L. N.; Lanz, L.; Smith, Howard. A.; Willner, S. P.; Klein, C.

    2015-05-01

    The Spitzer Interacting Galaxies Survey is a sample of 103 nearby galaxies in 48 systems, selected using association likelihoods and therefore free from disturbed morphology biases. All galaxies have been observed with Infrared Array Camera and MIPS 24 μm bands from the Spitzer Space Telescope. This catalog presents the global flux densities and colors of all systems and correlations between the interacting systems and their specific star formation rate (sSFR). This sample contains a wide variety of galaxy interactions with systems ranging in mass, mass ratios, and gas-content as well as interaction strength. This study seeks to identify the process of triggering star formation in galaxy interactions, therefore, we focus on the non-active galactic nucleus spiral galaxies only. From this subset of 70 spiral galaxies we have determined that this sample has enhanced sSFR compared to a sample of non-interacting field galaxies. Through optical data we have classified each system by “interaction strength” the strongly interacting (Stage 4) galaxies have higher sSFR values than the weakly (Stage 2) and moderately (Stage 3) interacting systems. However, the Stage 2 and 3 systems have statistically identical sSFR properties, despite the lack of optical interaction signatures exhibited by the Stage 2 galaxies. We suggest that the similarity of sSFR in these stages could be a consequence of some of these Stage 2 systems actually being post-perigalactic and having had sufficient time for their tidal features to fade to undetectable levels. This interpretation is consistent with the correlation of sSFR with separation, which we have determined to have little variation up to 100 kpc.

  20. THE IMACS CLUSTER BUILDING SURVEY. II. SPECTRAL EVOLUTION OF GALAXIES IN THE EPOCH OF CLUSTER ASSEMBLY

    SciTech Connect

    Dressler, Alan; Oemler, Augustus Jr.; Poggianti, Bianca M.; Vulcani, Benedetta; Gladders, Michael D.; Abramson, Louis

    2013-06-10

    The IMACS Cluster Building Survey (ICBS) provides spectra of {approx}2200 galaxies 0.31 < z < 0.54 in five rich clusters (R {approx}< 5 Mpc) and the field. Infalling, dynamically cold groups with tens of members account for approximately half of the supercluster population, contributing to a growth in cluster mass of {approx}100% by the present day. The ICBS spectra distinguish non-star-forming (PAS) and poststarburst (PSB) from star-forming galaxies-continuously star-forming (CSF) or starbursts (SBH or SBO), identified by anomalously strong H{delta} absorption or [O II] emission. For the infalling cluster groups and similar field groups, we find a correlation between PAS+PSB fraction and group mass, indicating substantial ''preprocessing'' through quenching mechanisms that can turn star-forming galaxies into passive galaxies without the unique environment of rich clusters. SBH + SBO starburst galaxies are common, and they maintain an approximately constant ratio (SBH+SBO)/CSF Almost-Equal-To 25% in all environments-from field, to groups, to rich clusters. Similarly, while PSB galaxies strongly favor denser environments, PSB/PAS Almost-Equal-To 10%-20% for all environments. This result, and their timescale {tau} {approx} 500 Myr, indicates that starbursts are not signatures of a quenching mechanism that produces the majority of passive galaxies. We suggest instead that starbursts and poststarbursts signal minor mergers and accretions, in star-forming and passive galaxies, respectively, and that the principal mechanisms for producing passive systems are (1) early major mergers, for elliptical galaxies, and (2) later, less violent processes-such as starvation and tidal stripping, for S0 galaxies.

  1. Lambda = 3 mm line survey of nearby active galaxies

    NASA Astrophysics Data System (ADS)

    Aladro, R.; Martín, S.; Riquelme, D.; Henkel, C.; Mauersberger, R.; Martín-Pintado, J.; Weiß, A.; Lefevre, C.; Kramer, C.; Requena-Torres, M. A.; Armijos-Abendaño, R. J.

    2015-07-01

    Aims: We aim to better understand the imprints that the nuclear activity in galaxies leaves in the molecular gas. Methods: We used the IRAM 30 m telescope to observe the frequency range ~[86-116] GHz towards the central regions of the starburst galaxies M 83, M 82, and NGC 253, the galaxies hosting an active galactic nucleus (AGN) M 51, NGC 1068, and NGC 7469, and the ultra-luminous infrared galaxies (ULIRGs) Arp 220 and Mrk 231. Assuming local thermodynamic equilibrium (LTE), we calculated the column densities of 27 molecules and 10 isotopologues (or their upper limits in case of non-detections). Results: Among others, we report the first tentative detections of CH3CHO, HNCO, and NS in M 82 and, for the first time in the extragalactic medium, HC5N in NGC 253. Hα recombination lines were only found in M 82 and NGC 253. Vibrationally excited lines of HC3N were only detected in Arp 220. CH3CCH emission is only seen in the starburst-dominated galaxies. By comparison of the fractional abundances among the galaxies, we looked for the molecules that are best suited to characterise the chemistry of each group of galaxies (starbursts, AGNs and ULIRGs), as well as the differences among galaxies within the same group. Conclusions: Suitable species for characterising and comparing starburst galaxies are CH3OH and HNCO as tracers of large-scale shocks, which dominate early to intermediate starburst stages, and CH3CCH, c-C3H2, and HCO as tracers of UV fields, which control the intermediate-to-old or post starburst phases. M 83 shows signs of a shock-dominated environment. NGC 253 is characterised by both strong shocks and some UV fields. M 82 stands out for its bright photo-dissociated region tracers, which indicate an UV field-dominated environment. Regarding AGNs, the abundances of HCN and CN (previously claimed as enhanced in AGNs) in M 51 are similar to those in starburst galaxies, while the HCN/HCO+ ratio is high in M 51 and NGC 1068, but not in NGC 7469. We did not find

  2. The Survey for Ionization in Neutral Gas Galaxies. I. Description and Initial Results

    NASA Astrophysics Data System (ADS)

    Meurer, Gerhardt R.; Hanish, D. J.; Ferguson, H. C.; Knezek, P. M.; Kilborn, V. A.; Putman, M. E.; Smith, R. C.; Koribalski, B.; Meyer, M.; Oey, M. S.; Ryan-Weber, E. V.; Zwaan, M. A.; Heckman, T. M.; Kennicutt, R. C., Jr.; Lee, J. C.; Webster, R. L.; Bland-Hawthorn, J.; Dopita, M. A.; Freeman, K. C.; Doyle, M. T.; Drinkwater, M. J.; Staveley-Smith, L.; Werk, J.

    2006-07-01

    We introduce the Survey for Ionization in Neutral Gas Galaxies (SINGG), a census of star formation in H I-selected galaxies. The survey consists of Hα and R-band imaging of a sample of 468 galaxies selected from the H I Parkes All Sky Survey (HIPASS). The sample spans three decades in H I mass and is free of many of the biases that affect other star-forming galaxy samples. We present the criteria for sample selection, list the entire sample, discuss our observational techniques, and describe the data reduction and calibration methods. This paper focuses on 93 SINGG targets whose observations have been fully reduced and analyzed to date. The majority of these show a single emission line galaxy (ELG). We see multiple ELGs in 13 fields, with up to four ELGs in a single field. All of the targets in this sample are detected in Hα, indicating that dormant (non-star-forming) galaxies with MHI>~3×107 Msolar are very rare. A database of the measured global properties of the ELGs is presented. The ELG sample spans 4 orders of magnitude in luminosity (Hα and R band), and Hα surface brightness, nearly 3 orders of magnitude in R surface brightness and nearly 2 orders of magnitude in Hα equivalent width (EW). The surface brightness distribution of our sample is broader than that of the Sloan Digital Sky Survey (SDSS) spectroscopic sample, the EW distribution is broader than prism-selected samples, and the morphologies found include all common types of star-forming galaxies (e.g., irregular, spiral, blue compact dwarf, starbursts, merging and colliding systems, and even residual star formation in S0 and Sa spirals). Thus, SINGG presents a superior census of star formation in the local universe suitable for further studies ranging from the analysis of H II regions to determination of the local cosmic star formation rate density.

  3. The SAGES Legacy Unifying Globulars and Galaxies survey (SLUGGS): sample definition, methods, and initial results

    SciTech Connect

    Brodie, Jean P.; Romanowsky, Aaron J.; Jennings, Zachary G.; Pota, Vincenzo; Kader, Justin; Roediger, Joel C.; Villaume, Alexa; Arnold, Jacob A.; Woodley, Kristin A.; Strader, Jay; Forbes, Duncan A.; Pastorello, Nicola; Usher, Christopher; Blom, Christina; Kartha, Sreeja S.; Foster, Caroline; Spitler, Lee R.

    2014-11-20

    We introduce and provide the scientific motivation for a wide-field photometric and spectroscopic chemodynamical survey of nearby early-type galaxies (ETGs) and their globular cluster (GC) systems. The SAGES Legacy Unifying Globulars and GalaxieS (SLUGGS) survey is being carried out primarily with Subaru/Suprime-Cam and Keck/DEIMOS. The former provides deep gri imaging over a 900 arcmin{sup 2} field-of-view to characterize GC and host galaxy colors and spatial distributions, and to identify spectroscopic targets. The NIR Ca II triplet provides GC line-of-sight velocities and metallicities out to typically ∼8 R {sub e}, and to ∼15 R {sub e} in some cases. New techniques to extract integrated stellar kinematics and metallicities to large radii (∼2-3 R {sub e}) are used in concert with GC data to create two-dimensional (2D) velocity and metallicity maps for comparison with simulations of galaxy formation. The advantages of SLUGGS compared with other, complementary, 2D-chemodynamical surveys are its superior velocity resolution, radial extent, and multiple halo tracers. We describe the sample of 25 nearby ETGs, the selection criteria for galaxies and GCs, the observing strategies, the data reduction techniques, and modeling methods. The survey observations are nearly complete and more than 30 papers have so far been published using SLUGGS data. Here we summarize some initial results, including signatures of two-phase galaxy assembly, evidence for GC metallicity bimodality, and a novel framework for the formation of extended star clusters and ultracompact dwarfs. An integrated overview of current chemodynamical constraints on GC systems points to separate, in situ formation modes at high redshifts for metal-poor and metal-rich GCs.

  4. The statistical investigation of the First and Second Byurakan survey galaxies and their neighbors

    NASA Astrophysics Data System (ADS)

    Nazaryan, Tigran A.

    2014-05-01

    In the thesis we study close pairs of galaxies with the aim of understanding the influence of gravitational interaction on nuclear activity and star formation of paired galaxies. For this purpose we investigate dependences of integral parameters of galaxies, their star formation and properties of nuclei on kinematic parameters of systems and their large-scale environment. The thesis has an introduction, three main chapters, a summary, lists of abbreviations and references, and three appendices. In the first chapter, the methods of selection of sample of pairs of galaxies and measurements of physical parameters of the First Byurakan Survey (Markarian) galaxies and their neighbors are presented, and the databases in appendices A and B are described, which contain parameters of neighbors of Markarian galaxies measured by us, and the parameters of pairs having Markarian galaxies, based on the Sloan Digital Sky Survey (SDSS) data. The selection effects of sample of pairs are discussed, and the statistical comparison of Markarian galaxies and their neighbors is done. The results of statistical study of star formation and activity of nuclei in pairs having Markarian galaxies are presented, as well as the correlations between properties of galaxies in pairs and the physical mechanisms behind them. In the second chapter, the results of statistical study of the Second Byurakan Survey (SBS) galaxies and their neighbors, and star formation and activity of nuclei in those pairs are presented and discussed. In the third chapter, possibilities of using supernovae as indicators of star formation are discussed, the sample of supernovae in pairs of galaxies is presented, and study of star formation in pairs of interacting galaxies by means of that sample of supernovae is done. Also а conclusion about the nature of progenitors of different types of supernovae is made. The short summary of main results of the study concludes the thesis. The thesis has 158 pages. The main results

  5. THE JAMES CLERK MAXWELL TELESCOPE NEARBY GALAXIES LEGACY SURVEY. II. WARM MOLECULAR GAS AND STAR FORMATION IN THREE FIELD SPIRAL GALAXIES

    SciTech Connect

    Warren, B. E.; Wilson, C. D.; Sinukoff, E.; Israel, F. P.; Van der Werf, P. P.; Serjeant, S.; Bendo, G. J.; Clements, D. L.; Brinks, E.; Irwin, J. A.; Knapen, J. H.; Leech, J.; Tan, B. K.; Matthews, H. E.; Muehle, S.; Mortimer, A. M. J.; Petitpas, G.; Spekkens, K.; Tilanus, R. P. J.; Usero, A. E-mail: wilson@physics.mcmaster.c E-mail: israel@strw.leidenuniv.n

    2010-05-01

    We present the results of large-area {sup 12}CO J = 3-2 emission mapping of three nearby field galaxies, NGC 628, NGC 3521, and NGC 3627, completed at the James Clerk Maxwell Telescope as part of the Nearby Galaxies Legacy Survey. These galaxies all have moderate to strong {sup 12}CO J = 3-2 detections over large areas of the fields observed by the survey, showing resolved structure and dynamics in their warm/dense molecular gas disks. All three galaxies were part of the Spitzer Infrared Nearby Galaxies Survey sample, and as such have excellent published multiwavelength ancillary data. These data sets allow us to examine the star formation properties, gas content, and dynamics of these galaxies on sub-kiloparsec scales. We find that the global gas depletion time for dense/warm molecular gas in these galaxies is consistent with other results for nearby spiral galaxies, indicating this may be independent of galaxy properties such as structures, gas compositions, and environments. Similar to the results from The H I Nearby Galaxy Survey, we do not see a correlation of the star formation efficiency with the gas surface density consistent with the Schmidt-Kennicutt law. Finally, we find that the star formation efficiency of the dense molecular gas traced by {sup 12}CO J = 3-2 is potentially flat or slightly declining as a function of molecular gas density, the {sup 12}CO J = 3-2/J = 1-0 ratio (in contrast to the correlation found in a previous study into the starburst galaxy M83), and the fraction of total gas in molecular form.

  6. The ESO nearby Abell cluster survey. VII. Galaxy density profiles of rich clusters of galaxies

    NASA Astrophysics Data System (ADS)

    Adami, C.; Mazure, A.; Katgert, P.; Biviano, A.

    1998-08-01

    We have analyzed the projected galaxy distributions in a subset of the ENACS cluster sample, viz. in those 77 clusters that have z < 0.1 and R_ACO >= 1 and for which ENACS and COSMOS data are available. For 20 % of these, the distribution of galaxies in the COSMOS catalogue does not allow a reliable centre position to be determined. For the other 62 clusters, we first determined the centre and elongation of the galaxy distribution. Subsequently, we made Maximum-Likelihood fits to the distribution of COSMOS galaxies for 4 theoretical profiles, two with `cores' (generalized King- and Hubble-profiles) and two with `cusps' (generalized Navarro, Frenk and White, or NFW, and de Vaucouleurs profiles). We obtain average core radii (or characteristic radii for the profiles without core) of 128, 189, 292 and 1582 kpc for fits with King, Hubble, NFW and de Vaucouleurs profiles respectively, with dispersions around these average values of 88, 116, 191 and 771 kpc. The surface density of background galaxies is about 4 10(-5) gals arcsec(-2) (with a spread of about 2 10(-5) ), and there is very good agreement between the values found for the 4 profiles. There is also very good agreement on the outer logarithmic slope of the projected galaxy distribution, which is that for the non-generalized King- and Hubble-profile (i.e. beta_ {King} = beta_ {Hubble} = 1, with the corresponding values for the two other model-profiles). We use the Likelihood ratio to investigate whether the observations are significantly better described by profiles with cusps or by profiles with cores. Taking the King and NFW profiles as `model' of either class, we find that about 75 % of the clusters are better fit by the King profile than by the NFW profile. However, for the individual clusters the preference for the King profile is rarely significant at a confidence level of more than 90 %. When we limit ourselves to the central regions it appears that the signifance increases drastically, with 65 % of the

  7. GALAXY CLUSTERING IN THE COMPLETED SDSS REDSHIFT SURVEY: THE DEPENDENCE ON COLOR AND LUMINOSITY

    SciTech Connect

    Zehavi, Idit; Zheng Zheng; Weinberg, David H.; Blanton, Michael R.; Bahcall, Neta A.; Gunn, James E.; Lupton, Robert H.; Strauss, Michael A.; Berlind, Andreas A.; Brinkmann, Jon; Frieman, Joshua A.; Nichol, Robert C.; Percival, Will J.; Schneider, Donald P.; Skibba, Ramin A.; Tegmark, Max; York, Donald G.

    2011-07-20

    We measure the luminosity and color dependence of galaxy clustering in the largest-ever galaxy redshift survey, the main galaxy sample of the Sloan Digital Sky Survey Seventh Data Release. We focus on the projected correlation function w{sub p} (r{sub p}) of volume-limited samples, extracted from the parent sample of {approx}700,000 galaxies over 8000 deg{sup 2}, extending up to redshift of 0.25. We interpret our measurements using halo occupation distribution (HOD) modeling assuming a {Lambda}CDM cosmology (inflationary cold dark matter with a cosmological constant). The amplitude of w{sub p} (r{sub p}) grows slowly with luminosity for L < L{sub *} and increases sharply at higher luminosities, with a large-scale bias factor b(> L) x ({sigma}{sub 8}/0.8) = 1.06 + 0.21(L/L{sub *}){sup 1.12}, where L is the sample luminosity threshold. At fixed luminosity, redder galaxies exhibit a higher amplitude and steeper correlation function, a steady trend that runs through the 'blue cloud' and 'green valley' and continues across the 'red sequence'. The cross-correlation of red and blue galaxies is close to the geometric mean of their autocorrelations, dropping slightly below at r{sub p} < 1 h{sup -1} Mpc. The luminosity trends for the red and blue galaxy populations separately are strikingly different. Blue galaxies show a slow but steady increase of clustering strength with luminosity, with nearly constant shape of w{sub p} (r{sub p}). The large-scale clustering of red galaxies shows little luminosity dependence until a sharp increase at L > 4 L{sub *}, but the lowest luminosity red galaxies (0.04-0.25 L{sub *}) show very strong clustering on small scales (r{sub p} < 2 h{sup -1} Mpc). Most of the observed trends can be naturally understood within the {Lambda}CDM+HOD framework. The growth of w{sub p} (r{sub p}) for higher luminosity galaxies reflects an overall shift in the mass scale of their host dark matter halos, in particular an increase in the minimum host halo mass M

  8. Measuring Low Mass Galaxies In The WFC3 Infrared Spectroscopic Parallels Survey

    NASA Astrophysics Data System (ADS)

    Colbert, James; Teplitz, Harry; Scarlata, Claudia; Siana, Brian; Malkan, Matt; McCarthy, Patrick; Henry, Alaina; Atek, Hakim; Fosbury, Robert; Ross, Nathanial; Hathi, Nimish; Bridge, Carrie; Bunker, Andrew; Dressler, Alan; Shim, Hyunjin; Bedregal, Alejandro; Dominguez, Alberto; Rafelski, Marc; Masters, Dan; Martin, Crystal; Dai, Sophia

    2015-10-01

    The WFC3 Infrared Spectroscopic Parallel (WISP) Survey uses over 1800 HST orbits to study galaxy evolution over a majority of cosmic history. Its slitless grism spectroscopy over a wide, continuous spectral range (0.8-1.7 micron) provides an unbiased selection of thousands of emission line galaxies over 0.5 < z < 2.5. Hundreds of these galaxies are detected in multiple emission lines, allowing for important diagnostics of metallicity and dust extinction. We propose deep 3.6 micron imaging (5 sigma, 0.9 micro-Jy) of 60 of the deepest WISP fields observed with the combination of G102+G141 grisms, in order to detect emission-line galaxies down to 0.1 L* and masses below 10^8 Mo. Combined with our HST optical and near-IR photometry, these IRAC data will be critical to determining accurate stellar masses for both passive and active galaxies in our survey. We will determine the evolution of the faint end slope of the stellar mass function and the mass-metallicity relation down to low-mass galaxies. The addition of the IRAC photometry will also provide much stronger constraints on dust extinction and star formation history, especially when combined with information available from the emission lines themselves.

  9. Obscured starbursts in galaxy clusters: a MIPS survey of z=0.5 clusters

    NASA Astrophysics Data System (ADS)

    Smail, Ian; Ebeling, Harald; Edge, Alastair; Geach, Jim; Ma, Cheng-Jiun; Wardlow, Julie

    2008-03-01

    We propose panoramic MIPS 24um imaging of four intermediate redshift (z~0.5) clusters selected from the MACS X-ray Survey. We will combine these with observations of four clusters at the same epoch from our pilot study (which span a broader range in mass) to parameterize the evolutionary sequence of infalling field galaxies in terms of the cluster global structure. This analysis will distinguish between the role of global and local environment in determining the star formation histories of starburst galaxies entering the cluster potential from the low-density field. Our previous successful MIPS project has yielded some exciting results - in particular the existence of large populations of starburst galaxies in z~0.5 clusters with strong PAH emission - which have been completely overlooked by previous optical/near-IR surveys of these well-studied systems. These are potentially the missing link between distant spirals and the local passive S0 galaxies which are the dominant population in local clusters. Our initial results point to a strong dependence of star formation on specific cluster properties - either the dynamical state or the cluster mass (or equivalently temperature of the ICM). By specifically targeting four clusters with a narrow range in mass, but a wide range of structures, we aim to determine the key drivers of the variation in the starburst population within clusters. This will provide vital clues as to the physics of environmental transformations of galaxies: an important ingredient of current galaxy evolution models.

  10. THE ACS NEARBY GALAXY SURVEY TREASURY. IX. CONSTRAINING ASYMPTOTIC GIANT BRANCH EVOLUTION WITH OLD METAL-POOR GALAXIES

    SciTech Connect

    Girardi, Leo; Williams, Benjamin F.; Gilbert, Karoline M.; Rosenfield, Philip; Dalcanton, Julianne J.; Marigo, Paola; Boyer, Martha L.; Dolphin, Andrew; Weisz, Daniel R.; Skillman, Evan; Melbourne, Jason; Olsen, Knut A. G.; Seth, Anil C.

    2010-12-01

    In an attempt to constrain evolutionary models of the asymptotic giant branch (AGB) phase at the limit of low masses and low metallicities, we have examined the luminosity functions and number ratios between AGB and red giant branch (RGB) stars from a sample of resolved galaxies from the ACS Nearby Galaxy Survey Treasury. This database provides Hubble Space Telescope optical photometry together with maps of completeness, photometric errors, and star formation histories for dozens of galaxies within 4 Mpc. We select 12 galaxies characterized by predominantly metal-poor populations as indicated by a very steep and blue RGB, and which do not present any indication of recent star formation in their color-magnitude diagrams. Thousands of AGB stars brighter than the tip of the RGB (TRGB) are present in the sample (between 60 and 400 per galaxy), hence, the Poisson noise has little impact in our measurements of the AGB/RGB ratio. We model the photometric data with a few sets of thermally pulsing AGB (TP-AGB) evolutionary models with different prescriptions for the mass loss. This technique allows us to set stringent constraints on the TP-AGB models of low-mass, metal-poor stars (with M < 1.5 M{sub sun}, [Fe/H]{approx}< -1.0). Indeed, those which satisfactorily reproduce the observed AGB/RGB ratios have TP-AGB lifetimes between 1.2 and 1.8 Myr, and finish their nuclear burning lives with masses between 0.51 and 0.55 M{sub sun}. This is also in good agreement with recent observations of white dwarf masses in the M4 old globular cluster. These constraints can be added to those already derived from Magellanic Cloud star clusters as important mileposts in the arduous process of calibrating AGB evolutionary models.

  11. FAINT TIDAL FEATURES IN GALAXIES WITHIN THE CANADA-FRANCE-HAWAII TELESCOPE LEGACY SURVEY WIDE FIELDS

    SciTech Connect

    Atkinson, Adam M.; Abraham, Roberto G.; Ferguson, Annette M. N.

    2013-03-01

    We present an analysis of the detectability of faint tidal features in galaxies from the wide-field component of the Canada-France-Hawaii Telescope Legacy Survey. Our sample consists of 1781 luminous (M{sub r{sup '}}<-19.3 mag) galaxies in the magnitude range 15.5 mag < r' < 17 mag and in the redshift range 0.04 < z < 0.2. Although we have classified tidal features according to their morphology (e.g., streams, shells, and tails), we do not attempt to interpret them in terms of their physical origin (e.g., major versus minor merger debris). Instead, we provide a catalog that is intended to provide raw material for future investigations which will probe the nature of low surface brightness substructure around galaxies. We find that around 12% of the galaxies in our sample show clear tidal features at the highest confidence level. This fraction rises to about 18% if we include systems with convincing, albeit weaker tidal features, and to 26% if we include systems with more marginal features that may or may not be tidal in origin. These proportions are a strong function of rest-frame color and of stellar mass. Linear features, shells, and fans are much more likely to occur in massive galaxies with stellar masses >10{sup 10.5} M {sub Sun }, and red galaxies are twice as likely to show tidal features than are blue galaxies.

  12. GALAXY ZOO MORPHOLOGY AND PHOTOMETRIC REDSHIFTS IN THE SLOAN DIGITAL SKY SURVEY

    SciTech Connect

    Way, M. J.

    2011-06-10

    It has recently been demonstrated that one can accurately derive galaxy morphology from particular primary and secondary isophotal shape estimates in the Sloan Digital Sky Survey (SDSS) imaging catalog. This was accomplished by applying Machine Learning techniques to the Galaxy Zoo morphology catalog. Using the broad bandpass photometry of the SDSS in combination with precise knowledge of galaxy morphology should help in estimating more accurate photometric redshifts for galaxies. Using the Galaxy Zoo separation for spirals and ellipticals in combination with SDSS photometry we attempt to calculate photometric redshifts. In the best case we find that the root-mean-square error for luminous red galaxies classified as ellipticals is as low as 0.0118. Given these promising results we believe better photometric redshift estimates for all galaxies in the SDSS ({approx}350 million) will be feasible if researchers can also leverage their derived morphologies via Machine Learning. These initial results look to be promising for those interested in estimating weak lensing, baryonic acoustic oscillation, and other fields dependent upon accurate photometric redshifts.

  13. THE RINGS SURVEY. I. Hα AND H i VELOCITY MAPS OF GALAXY NGC 2280

    SciTech Connect

    Mitchell, Carl J.; Williams, T. B.; Sellwood, J. A.; Spekkens, Kristine; Lee-Waddell, K.; Naray, Rachel Kuzio de E-mail: williams@saao.ac.za E-mail: karen.lee-waddell@rmc.ca E-mail: sellwood@physics.rutgers.edu

    2015-03-15

    Precise measurements of gas kinematics in the disk of a spiral galaxy can be used to estimate its mass distribution. The Southern African Large Telescope has a large collecting area and field of view, and is equipped with a Fabry–Pérot (FP) interferometer that can measure gas kinematics in a galaxy from the Hα line. To take advantage of this capability, we have constructed a sample of 19 nearby spiral galaxies, the RSS Imaging and Spectroscopy Nearby Galaxy Survey, as targets for detailed study of their mass distributions and have collected much of the needed data. In this paper, we present velocity maps produced from Hα FP interferometry and H i aperture synthesis for one of these galaxies, NGC 2280, and show that the two velocity measurements are generally in excellent agreement. Minor differences can mostly be attributed to the different spatial distributions of the excited and neutral gas in this galaxy, but we do detect some anomalous velocities in our Hα velocity map of the kind that have previously been detected in other galaxies. Models produced from our two velocity maps agree well with each other and our estimates of the systemic velocity and projection angles confirm previous measurements of these quantities for NGC 2280.

  14. Population gradients in the Sloan Digital Sky Survey Galaxy Catalogue: the role of merging

    NASA Astrophysics Data System (ADS)

    Tortora, C.; Napolitano, N. R.

    2012-04-01

    We investigate the role of the environment on the colour and stellar population gradients in a local sample of ˜3500 central and ˜1150 satellite Sloan Digital Sky Survey (SDSS) early-type galaxies. The environment is parametrized in terms of the number of satellite galaxies, Ngal, in each group. For central galaxies, we find that both optical colour and mass-to-light (M/L) ratio gradients are shallower in central galaxies residing in denser environments (higher Ngal). This trend is driven by metallicity gradients, while age gradients appear to be less dependent on the environment and to have a larger scatter. On the other hand, satellites do not show any differences in terms of the environment. The same results are found if galaxies are classified by central age, and both central and satellite galaxies have shallower gradients if they are older and steeper gradients if younger, satellites being independent of ages. In central galaxies, we show that the observed trends can be explained with the occurrence of dry mergings, which are more numerous in denser environments and producing shallower colour gradients because of more uniform metallicity distributions due to the mixing of stellar populations, while no final clues about merging occurrence can be obtained for satellites. Finally, we discuss all systematics on stellar population fitting and their impact on the final results.

  15. Simulating Compact Elliptical Galaxy Formation by Tidal Stripping for Comparison to the RESOLVE Survey

    NASA Astrophysics Data System (ADS)

    Ray, Christine; Snyder, Elaine M.; Kannappan, Sheila; Sinha, Manodeep; RESOLVE Team

    2016-01-01

    Observations of compact elliptical galaxies (cEs) have uncovered abnormally high velocity dispersions and surface brightnesses for objects of their mass. These properties indicate that they may be the tidally stripped remnants of larger disk galaxies. We test this tidal stripping scenario using N-body simulations of cE formation with the Gadget-2 code. We track the velocity dispersions of stellar particles within the half-light radius throughout our simulations, which allows us to compare our simulated galaxies with velocity dispersion data for cEs in the RESOLVE survey. We first consider initial conditions similar to published work, which report stripping of a large spiral galaxy (stellar mass ~ 10^11 solar masses) to cE size in a cluster potential. We find that the density of the disk galaxy is too high to allow it to lose particles to the less dense cluster. We argue that the initial position of the galaxy with respect to the cluster as well as the large size of the cluster particles in comparison to the size of the galaxy particles artificially heightened the stripping percentages reported in previous work. We hypothesize that only a dwarf galaxy with a shallower density profile can be stripped to cE size, and we present initial efforts to test this idea. We simulate a dwarf galaxy based on a real system in the RESOLVE survey, with stellar mass 10^9 solar masses and half-light radius 1.15 kpc. Within ~700 pc our dwarf is denser than our cluster, suggesting the stripped remnant should be close to the size of RESOLVE cEs. This radius contains approximately 13% of the total stellar mass of the galaxy, or ~2 x 10^8 solar masses. We therefore expect our stripped remnant to be at least this massive, although the impact parameter of the orbit will determine how much mass is actually removed. We discuss the position of our simulated galaxies compared to RESOLVE cEs in the velocity dispersion vs. mass plane. This research has been supported by National Science

  16. No galaxy left behind: accurate measurements with the faintest objects in the Dark Energy Survey

    NASA Astrophysics Data System (ADS)

    Suchyta, E.; Huff, E. M.; Aleksić, J.; Melchior, P.; Jouvel, S.; MacCrann, N.; Ross, A. J.; Crocce, M.; Gaztanaga, E.; Honscheid, K.; Leistedt, B.; Peiris, H. V.; Rykoff, E. S.; Sheldon, E.; Abbott, T.; Abdalla, F. B.; Allam, S.; Banerji, M.; Benoit-Lévy, A.; Bertin, E.; Brooks, D.; Burke, D. L.; Rosell, A. Carnero; Kind, M. Carrasco; Carretero, J.; Cunha, C. E.; D'Andrea, C. B.; da Costa, L. N.; DePoy, D. L.; Desai, S.; Diehl, H. T.; Dietrich, J. P.; Doel, P.; Eifler, T. F.; Estrada, J.; Evrard, A. E.; Flaugher, B.; Fosalba, P.; Frieman, J.; Gerdes, D. W.; Gruen, D.; Gruendl, R. A.; James, D. J.; Jarvis, M.; Kuehn, K.; Kuropatkin, N.; Lahav, O.; Lima, M.; Maia, M. A. G.; March, M.; Marshall, J. L.; Miller, C. J.; Miquel, R.; Neilsen, E.; Nichol, R. C.; Nord, B.; Ogando, R.; Percival, W. J.; Reil, K.; Roodman, A.; Sako, M.; Sanchez, E.; Scarpine, V.; Sevilla-Noarbe, I.; Smith, R. C.; Soares-Santos, M.; Sobreira, F.; Swanson, M. E. C.; Tarle, G.; Thaler, J.; Thomas, D.; Vikram, V.; Walker, A. R.; Wechsler, R. H.; Zhang, Y.; DES Collaboration

    2016-03-01

    Accurate statistical measurement with large imaging surveys has traditionally required throwing away a sizable fraction of the data. This is because most measurements have relied on selecting nearly complete samples, where variations in the composition of the galaxy population with seeing, depth, or other survey characteristics are small. We introduce a new measurement method that aims to minimize this wastage, allowing precision measurement for any class of detectable stars or galaxies. We have implemented our proposal in BALROG, software which embeds fake objects in real imaging to accurately characterize measurement biases. We demonstrate this technique with an angular clustering measurement using Dark Energy Survey (DES) data. We first show that recovery of our injected galaxies depends on a variety of survey characteristics in the same way as the real data. We then construct a flux-limited sample of the faintest galaxies in DES, chosen specifically for their sensitivity to depth and seeing variations. Using the synthetic galaxies as randoms in the Landy-Szalay estimator suppresses the effects of variable survey selection by at least two orders of magnitude. With this correction, our measured angular clustering is found to be in excellent agreement with that of a matched sample from much deeper, higher resolution space-based Cosmological Evolution Survey (COSMOS) imaging; over angular scales of 0.004° < θ < 0.2°, we find a best-fitting scaling amplitude between the DES and COSMOS measurements of 1.00 ± 0.09. We expect this methodology to be broadly useful for extending measurements' statistical reach in a variety of upcoming imaging surveys.

  17. No Galaxy Left Behind: Accurate Measurements with the Faintest Objects in the Dark Energy Survey

    DOE PAGES

    Suchyta, E.

    2016-01-27

    Accurate statistical measurement with large imaging surveys has traditionally required throwing away a sizable fraction of the data. This is because most measurements have have relied on selecting nearly complete samples, where variations in the composition of the galaxy population with seeing, depth, or other survey characteristics are small. We introduce a new measurement method that aims to minimize this wastage, allowing precision measurement for any class of stars or galaxies detectable in an imaging survey. We have implemented our proposal in Balrog, a software package which embeds fake objects in real imaging in order to accurately characterize measurement biases.more » We also demonstrate this technique with an angular clustering measurement using Dark Energy Survey (DES) data. We first show that recovery of our injected galaxies depends on a wide variety of survey characteristics in the same way as the real data. We then construct a flux-limited sample of the faintest galaxies in DES, chosen specifically for their sensitivity to depth and seeing variations. Using the synthetic galaxies as randoms in the standard LandySzalay correlation function estimator suppresses the effects of variable survey selection by at least two orders of magnitude. Now our measured angular clustering is found to be in excellent agreement with that of a matched sample drawn from much deeper, higherresolution space-based COSMOS imaging; over angular scales of 0.004° < θ < 0.2 ° , we find a best-fit scaling amplitude between the DES and COSMOS measurements of 1.00 ± 0.09. We expect this methodology to be broadly useful for extending the statistical reach of measurements in a wide variety of coming imaging surveys.« less

  18. The Sloan Lens ACS Survey. I. A Large Spectroscopically Selected Sample of Massive Early-Type Lens Galaxies

    NASA Technical Reports Server (NTRS)

    Bolton, Adam S.; Burles, Scott; Koopmans, Leon V. E.; Treu, Tommaso; Moustakas, Leonidas A.

    2006-01-01

    The Sloan Lens ACS (SLACS) Survey is an efficient Hubble Space Telescope (HST) Snapshot imaging survey for new galaxy-scale strong gravitational lenses. The targeted lens candidates are selected spectroscopically from the Sloan Digital Sky Survey (SDSS) database of galaxy spectra for having multiple nebular emission lines at a redshift significantly higher than that of the SDSS target galaxy. The SLACS survey is optimized to detect bright early-type lens galaxies with faint lensed sources in order to increase the sample of known gravitational lenses suitable for detailed lensing, photometric, and dynamical modeling. In this paper, the first in a series on the current results of our HST Cycle 13 imaging survey, we present a catalog of 19 newly discovered gravitational lenses, along with nine other observed candidate systems that are either possible lenses, nonlenses, or nondetections. The survey efficiency is thus >=68%. We also present Gemini 8 m and Magellan 6.5 m integral-field spectroscopic data for nine of the SLACS targets, which further support the lensing interpretation. A new method for the effective subtraction of foreground galaxy images to reveal faint background features is presented. We show that the SLACS lens galaxies have colors and ellipticities typical of the spectroscopic parent sample from which they are drawn (SDSS luminous red galaxies and quiescent MAIN sample galaxies), but are somewhat brighter and more centrally concentrated. Several explanations for the latter bias are suggested. The SLACS survey provides the first statistically significant and homogeneously selected sample of bright early-type lens galaxies, furnishing a powerful probe of the structure of early-type galaxies within the half-light radius. The high confirmation rate of lenses in the SLACS survey suggests consideration of spectroscopic lens discovery as an explicit science goal of future spectroscopic galaxy surveys.

  19. Measuring Large-Scale Structure at z ~ 1 with the VIPERS galaxy survey

    NASA Astrophysics Data System (ADS)

    Guzzo, Luigi

    2016-10-01

    The VIMOS Public Extragalactic Redshift Survey (VIPERS) is the largest redshift survey ever conducted with the ESO telescopes. It has used the Very Large Telescope to collect nearly 100,000 redshifts from the general galaxy population at 0.5 < z < 1.2. With a combination of volume and high sampling density that is unique for these redshifts, it allows statistical measurements of galaxy clustering and related cosmological quantities to be obtained on an equal footing with classic results from local redshift surveys. At the same time, the simple magnitude-limited selection and the wealth of ancillary photometric data provide a general view of the galaxy population, its physical properties and the relation of the latter to large-scale structure. This paper presents an overview of the galaxy clustering results obtained so far, together with their cosmological implications. Most of these are based on the ~ 55,000 galaxies forming the first public data release (PDR-1). As of January 2015, observations and data reduction are complete and the final data set of more than 90,000 redshifts is being validated and made ready for the final investigations.

  20. Resolving the extended stellar haloes of nearby galaxies: the wide-field PISCeS survey

    NASA Astrophysics Data System (ADS)

    Crnojevic, Denija; Sand, David J.; Caldwell, Nelson; Guhathakurta, Puragra; McLeod, Brian A.; Seth, Anil; Simon, Joshua D.; Strader, Jay; Toloba, Elisa

    2015-08-01

    I will present results from the wide-field Panoramic Imaging Survey of Centaurus and Sculptor (PISCeS): we investigate the resolved stellar haloes of two nearby galaxies (the spiral NGC253 and the elliptical Centaurus A, D~3.7 Mpc) out to a galactocentric radius of 150 kpc with Magellan/Megacam. The survey led to the discovery of ~20 faint satellites and stunning streams/substructures in two environments substantially different from the Local Group, i.e. the loose Sculptor group of galaxies and the Centaurus A group dominated by an elliptical. These discoveries clearly testify the past and ongoing accretion processes shaping the haloes of these nearby galaxies, and provide the first complete census of their satellite systems down to an unprecedented M_V<-8. This effectively enables the first direct comparison of external galaxies' resolved haloes to the PAndAS survey. The detailed characterization of the stellar content, shape and gradients in the extended haloes of NGC253, Centaurus A and in their satellites represent crucial constraints to theoretical models of galaxy formation and evolution.

  1. The CALIFA survey across the Hubble sequence. Spatially resolved stellar population properties in galaxies

    NASA Astrophysics Data System (ADS)

    González Delgado, R. M.; García-Benito, R.; Pérez, E.; Cid Fernandes, R.; de Amorim, A. L.; Cortijo-Ferrero, C.; Lacerda, E. A. D.; López Fernández, R.; Vale-Asari, N.; Sánchez, S. F.; Mollá, M.; Ruiz-Lara, T.; Sánchez-Blázquez, P.; Walcher, C. J.; Alves, J.; Aguerri, J. A. L.; Bekeraité, S.; Bland-Hawthorn, J.; Galbany, L.; Gallazzi, A.; Husemann, B.; Iglesias-Páramo, J.; Kalinova, V.; López-Sánchez, A. R.; Marino, R. A.; Márquez, I.; Masegosa, J.; Mast, D.; Méndez-Abreu, J.; Mendoza, A.; del Olmo, A.; Pérez, I.; Quirrenbach, A.; Zibetti, S.

    2015-09-01

    Various different physical processes contribute to the star formation and stellar mass assembly histories of galaxies. One important approach to understanding the significance of these different processes on galaxy evolution is the study of the stellar population content of today's galaxies in a spatially resolved manner. The aim of this paper is to characterize in detail the radial structure of stellar population properties of galaxies in the nearby universe, based on a uniquely large galaxy sample, considering the quality and coverage of the data. The sample under study was drawn from the CALIFA survey and contains 300 galaxies observed with integral field spectroscopy. These cover a wide range of Hubble types, from spheroids to spiral galaxies, while stellar masses range from M⋆ ~ 109 to 7 × 1011 M⊙. We apply the fossil record method based on spectral synthesis techniques to recover the following physical properties for each spatial resolution element in our target galaxies: the stellar mass surface density (μ⋆), stellar extinction (AV), light-weighted and mass-weighted ages (⟨log age⟩L, ⟨log age⟩M), and mass-weighted metallicity (⟨log Z⋆⟩M). To study mean trends with overall galaxy properties, the individual radial profiles are stacked in seven bins of galaxy morphology (E, S0, Sa, Sb, Sbc, Sc, and Sd). We confirm that more massive galaxies are more compact, older, moremetal rich, and less reddened by dust. Additionally, we find that these trends are preserved spatially with the radial distance to the nucleus. Deviations from these relations appear correlated with Hubble type: earlier types are more compact, older, and more metal rich for a given M⋆, which is evidence that quenching is related to morphology, but not driven by mass. Negative gradients of ⟨log age⟩L are consistent with an inside-out growth of galaxies, with the largest ⟨log age⟩L gradients in Sb-Sbc galaxies. Further, the mean stellar ages of disks and bulges are

  2. Redshift-Distance Survey of Early-Type Galaxies. I. The ENEARc Cluster Sample

    NASA Astrophysics Data System (ADS)

    Bernardi, M.; Alonso, M. V.; da Costa, L. N.; Willmer, C. N. A.; Wegner, G.; Pellegrini, P. S.; Rité, C.; Maia, M. A. G.

    2002-06-01

    This paper presents data on the ENEARc subsample of the larger ENEAR survey of nearby early-type galaxies. The ENEARc galaxies belong to clusters and were specifically chosen to be used for the construction of a Dn-σ template. The ENEARc sample includes new measurements of spectroscopic and photometric parameters (redshift, velocity dispersion, line index Mg2, and the angular diameter dn), as well as data from the literature. New spectroscopic data are given for 229 cluster early-type galaxies, and new photometry is presented for 348 objects. Repeat and overlap observations with external data sets are used to construct a final merged catalog consisting of 640 early-type galaxies in 28 clusters. Objective criteria, based on catalogs of groups of galaxies derived from complete redshift surveys of the nearby universe, are used to assign galaxies to clusters. In a companion paper, these data are used to construct the template Dn-σ distance relation for early-type galaxies, which has been used to estimate galaxy distances and derive peculiar velocities for the ENEAR all-sky sample. Based on observations at Complejo Astronomico El Leoncito, operated under agreement between the Consejo Nacional de Investigaciones Científicas de la República Argentina and the National Universities of La Plata, Córdoba, and San Juan; Cerro Tololo Inter-American Observatory, National Optical Astronomical Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under cooperative agreement with the National Science Foundation; the European Southern Observatory (ESO), partially under the ESO-ON agreement; the Fred Lawrence Whipple Observatory; the Observatório do Pico dos Dias, operated by the Laboratório Nacional de Astrofísica and the MDM Observatory at Kitt Peak.

  3. Spectral classification indicators of emission-line galaxies from the Sloan Digital Sky Survey

    NASA Astrophysics Data System (ADS)

    Shi, Fei; Liu, Yu-Yan; Li, Pei-Yu; Yu, Ming; Lei, Yu-Ming; Wang, Jian

    2015-07-01

    To find efficient spectral classification diagrams to classify emission-line galaxies, especially in large surveys and huge data bases, an artificial neural network (ANN) supervised learning algorithms is applied to a sample of emission-line galaxies from the Sloan Digital Sky Survey data release 9 provided by the Max Planck Institute and the Johns Hopkins University (MPA/JHU) (http://www.sdss3.org/dr9/spectro/spectroaccess.php). A two-step approach is adopted. (i) The ANN network must be trained with a subset of objects that are known to be active galactic nuclei (AGNs) hosts, composites or star-forming galaxies, treating the strong emission-line flux measurements as input feature vectors in n-dimensional space, where n is the number of strong emission-line flux ratios. (ii) After the network is trained on a sample of galaxies, the remaining galaxies are classified in the automatic test analysis as AGN hosts, composites or star-forming galaxies. We show that the classification diagrams based on the [N II]/Hα versus other emission-line ratio, such as [O III]/Hβ, [Ne III]/[O II], ([O III]λ4959 + [O III]λ5007)/[O III]λ4363, [O II]/Hβ, [Ar III]/[O III], [S II]/Hα, and [O I]/Hα, plus colour, allows us to separate unambiguously AGN hosts, composites or star-forming galaxies. Among them, the diagram of [N II]/Hα versus [O III]/Hβ achieved an accuracy of 98 per cent for classification of AGN hosts, composites or star-forming galaxies. The other diagrams above except the diagram of [N II]/Hα versus [O III]/Hβ give an accuracy of ˜90 per cent. The code in the paper is available on the web (http://fshi5388.blog.163.com).

  4. Scale-dependent galaxy bias in the Sloan Digital Sky Survey as a function of luminosity and colour

    NASA Astrophysics Data System (ADS)

    Cresswell, James G.; Percival, Will J.

    2009-01-01

    It has been known for a long time that the clustering of galaxies changes as a function of galaxy type. This galaxy bias acts as a hindrance to the extraction of cosmological information from the galaxy power spectrum or correlation function. Theoretical arguments show that a change in the amplitude of the clustering between galaxies and mass on large scales is unavoidable, but cosmological information can be easily extracted from the shape of the power spectrum or correlation function if this bias is independent of scale. Scale-dependent bias is generally small on large scales, k < 0.1hMpc-1, but on smaller scales can affect the recovery of Ωmh from the measured shape of the clustering signal, and have a small effect on the Baryon Acoustic Oscillations. In this paper, we investigate the transition from scale-independent to scale-dependent galaxy bias as a function of galaxy population. We use the Sloan Digital Sky Survey Data Release 5 sample to fit various models, which attempt to parametrize the turn-off from scale-independent behaviour. For blue galaxies, we find that the strength of the turn-off is strongly dependent on galaxy luminosity, with stronger scale-dependent bias on larger scales for more luminous galaxies. For red galaxies, the scale dependence is a weaker function of luminosity. Such trends need to be modelled in order to optimally extract the information available in future surveys, and can help with the design of such surveys.

  5. The Las Campanas Infrared Survey: Early-Type Galaxy Progenitors beyond z=1

    NASA Astrophysics Data System (ADS)

    McCarthy, P. J.; Carlberg, R. G.; Chen, H.-W.; Marzke, R. O.; Firth, A. E.; Ellis, R. S.; Persson, S. E.; McMahon, R. G.; Lahav, O.; Wilson, J.; Martini, P.; Abraham, R. G.; Sabbey, C. N.; Oemler, A.; Murphy, D. C.; Somerville, R. S.; Beckett, M. G.; Lewis, J. R.; MacKay, C. D.

    2001-10-01

    We have identified a population of faint red galaxies from a 0.62 deg2 region of the Las Campanas Infrared Survey whose properties are consistent with their being the progenitors of early-type galaxies. The optical and IR colors, number-magnitude relation, and angular clustering together indicate modest evolution and increased star formation rates among the early-type field population at redshifts between 1 and 2. The counts of red galaxies with H magnitudes between 17 and 20 rise with a slope that is much steeper than that of the total H sample. The surface density of red galaxies drops from roughly 3000 deg-2 at H=20.5, I-H>3 to ~20 deg-2 at H=20, I-H>5. The V-I colors are approximately 1.5 mag bluer on average than a pure old population and span a range of more than 3 mag. The strength of the angular clustering of the red galaxies is an order of magnitude larger than that of the full galaxy sample. The colors, and photometric redshifts derived from them, indicate that the red galaxies have redshift distributions adequately described by Gaussians with σz~=0.2 centered near z=1, with the exception that galaxies having V-I<1.6 and I-H>3 are primarily in the 1.5<~z<~2 range. We invert the angular correlation functions using these n(z) and find comoving correlation lengths of r0~=9-10 h-1 Mpc at z~=1, comparable to, or larger than, those found for early-type galaxies at lower redshifts. A simple photometric evolution model reproduces the counts of the red galaxies, with only an ~30% decline in the underlying space density of early-type galaxies at z~1.2. The colors indicate characteristic star formation rates of ~1 Msolar yr-1 per 1010 Msolar. We suggest on the basis of the colors, counts, and clustering that these red galaxies are the bulk of the progenitors of present-day early-type galaxies.

  6. Gas Dynamics in AGN Galaxies: First Results of the HI-NUGA Survey

    NASA Astrophysics Data System (ADS)

    Haan, S.; Schinnerer, E.; Mundell, C. G.; García-Burillo, S.; Combes, F.

    2007-05-01

    Active Galactic Nuclei (AGN) galaxies are generally known as very luminous galaxies where a small emitting region is associated with gas accretion onto a central supermassive black hole. Up to now the process of fueling the AGN with material (gas or stars) generally far away from the gravitational influence of the central black hole is controversial and not understood. Since the required material has to remove its high angular momentum in order to fall into the center, various mechanisms may play a role, including m = 2 perturbations (bars and spirals), m = 1 perturbations (spirals, warps, lopsidedness), tidal interactions between galaxies, and galaxy mergers. In order to study the gas transport from the outskirts to the centers of AGN galaxies, we are carrying out a key project, named NUGA (Nuclei of Galaxies), which is a high spectral and angular resolution CO and HI survey of low luminosity AGN in nearby galaxies (Seyferts, LINERs and transition objects). The complete dataset provides us with the unique opportunity to understand and ultimately model the whole disk kinematics on spatial scales ranging over several orders of magnitude. Here, we will present observations of 15 galaxies recently obtained in the 21 cm emission of neutral hydrogen using the Very Large Array. First results on the HI gas and velocity distribution of these galaxies are summarized and discussed. The derived properties, including the ratio of dynamical mass versus gas mass (+ stellar mass), will be presented and compared with the AGN activity types in order to search for possible dependences. Additionally, effects of satellites and tidal disturbances onto the HI disk as well as their correlation with AGN type and dynamical modes probed by CO (inner kpc) will be examined.

  7. Star Formation and Dense Gas in Galaxy Mergers from the VIXENS Survey

    NASA Astrophysics Data System (ADS)

    Heiderman, Amanda L.; VIXENS Team

    2016-01-01

    We present our λ= 3 mm IRAM and NRO single dish line survey for a sample of 15 interacting galaxies in the VIRUS-P Investigation of the eXtreme ENvironments of Starbursts (VIXENS) survey. Our sample of merging galaxies range from early to late interaction stages (close pairs to merger remnants, respectively). A variety of molecular lines are detected including dense gas tracers HCN, HCO+, HNC, CS, CN (and others) as well as 12CO and 13CO. We compare the dense gas fractions with 12CO and 13CO as well as star formation efficiencies defined by infrared-to-dense gas tracer luminosity ratio and discuss trends with interaction stage. We also investigate relations between star formation and dense gas content in our merger sample and compare them to non-interacting star forming galaxies and Galactic star forming regions in the Milky Way.

  8. Spectral classification of emission-line galaxies from the Sloan Digital Sky Survey. I. An improved classification for high-redshift galaxies

    NASA Astrophysics Data System (ADS)

    Lamareille, F.

    2010-01-01

    Aims: We study the spectral classification of emission-line galaxies as starforming galaxies or active galactic nuclei (AGNs). With the high-quality data from the Sloan Digital Sky Survey (SDSS) we define an improved classification to be used for high-redshift galaxies. Methods: We classify emission-line galaxies of the SDSS according to the latest standard recipe using [Oiii]λ5007, [Nii]λ6584, [Sii]λ6717+6731, Hα, and Hβ emission lines. We obtain four classes: starforming galaxies, Seyfert 2, LINERs, and composites. We then examine where these galaxies fall in the blue diagram used at high redshift (i.e. log([Oiii]λ5007/Hβ) vs. log([Oii]λλ3726+3729/Hβ). Results: We define new improved boundaries in the blue diagram for starforming galaxies, Seyfert 2, LINERs, SF/Sy2, and SF-LIN/comp classes. We maximize the success rate to 99.7% for the detection of starforming galaxies to 86% for the Seyfert 2 (including the SF/Sy2 region) and to 91% for the LINERs. We also minimize the contamination to 16% in the region of starforming galaxies. We cannot reliably separate composites from starforming galaxies and LINERs, but we define an SF-LIN/comp region where most of them fall (64%).

  9. EVOLUTION OF GROUP GALAXIES FROM THE FIRST RED-SEQUENCE CLUSTER SURVEY

    SciTech Connect

    Li, I. H.; Yee, H. K. C.; Hsieh, B. C.; Gladders, M. E-mail: hyee@astro.utoronto.ca E-mail: gladders@oddjob.uchicago.edu

    2012-04-20

    We study the evolution of the red-galaxy fraction (f{sub red}) in 905 galaxy groups with 0.15 {<=} z < 0.52. The galaxy groups are identified by the 'probability friends-of-friends' algorithm from the first Red-Sequence Cluster Survey (RCS1) photometric-redshift sample. There is a high degree of uniformity in the properties of the red sequence of the group galaxies, indicating that the luminous red-sequence galaxies in the groups are already in place by z {approx} 0.5 and that they have a formation epoch of z {approx}> 2. In general, groups at lower redshifts exhibit larger f{sub red} than those at higher redshifts, showing a group Butcher-Oemler effect. We investigate the evolution of f{sub red} by examining its dependence on four parameters, one of which can be classified as intrinsic and three of which can be classified as environmental: galaxy stellar mass (M{sub *}), total group stellar mass (M{sub *,grp}, a proxy for group halo mass), normalized group-centric radius (r{sub grp}), and local galaxy density ({Sigma}{sub 5}). We find that M{sub *} is the dominant parameter such that there is a strong correlation between f{sub red} and galaxy stellar mass. Furthermore, the dependence of f{sub red} on the environmental parameters is also a strong function of M{sub *}. Massive galaxies (M{sub *} {approx}> 10{sup 11} M{sub Sun }) show little dependence of f{sub red} on r{sub grp}, M{sub *,grp}, and {Sigma}{sub 5} over the redshift range. The dependence of f{sub red} on these parameters is primarily seen for galaxies with lower masses, especially for M{sub *} {approx}< 10{sup 10.6} M{sub Sun }. We observe an apparent 'group down-sizing' effect, in that galaxies in lower-mass halos, after controlling for galaxy stellar mass, have lower f{sub red}. We find a dependence of f{sub red} on both r{sub grp} and {Sigma}{sub 5} after the other parameters are controlled. At a fixed r{sub grp}, there is a significant dependence of f{sub red} on {Sigma}{sub 5}, while r{sub grp

  10. The power spectrum of galaxies in the 2dF 100k redshift survey

    NASA Astrophysics Data System (ADS)

    Tegmark, Max; Hamilton, Andrew J. S.; Xu, Yongzhong

    2002-10-01

    We compute the real-space power spectrum and the redshift-space distortions of galaxies in the 2dF 100k galaxy redshift survey using pseudo-Karhunen-Loève eigenmodes and the stochastic bias formalism. Our results agree well with those published by the 2dFGRS team, and have the added advantage of producing easy-to-interpret uncorrelated minimum-variance measurements of the galaxy-galaxy, galaxy-velocity and velocity-velocity power spectra in 27 k-bands, with narrow and well-behaved window functions in the range 0.01 h Mpc-1 < k < 0.8 h Mpc-1. We find no significant detection of baryonic wiggles, although our results are consistent with a standard flat ΩΛ= 0.7`concordance' model and previous tantalizing hints of baryonic oscillations. We measure the galaxy-matter correlation coefficient r > 0.4 and the redshift-distortion parameter β= 0.49 +/- 0.16 for r= 1 (β= 0.47 +/- 0.16 without finger-of-god compression). Since this is an apparent-magnitude limited sample, luminosity-dependent bias may cause a slight red-tilt in the power spectrum. A battery of systematic error tests indicate that the survey is not only impressive in size, but also unusually clean, free of systematic errors at the level to which our tests are sensitive. Our measurements and window functions are available at http://www.hep.upenn.edu/~max/2df.html together with the survey mask, radial selection function and uniform subsample of the survey that we have constructed.

  11. ZFIRE: A KECK/MOSFIRE Spectroscopic Survey of Galaxies in Rich Environments at z ˜ 2

    NASA Astrophysics Data System (ADS)

    Nanayakkara, Themiya; Glazebrook, Karl; Kacprzak, Glenn G.; Yuan, Tiantian; Tran, Kim-Vy; Spitler, Lee; Kewley, Lisa; Straatman, Caroline; Cowley, Michael; Fisher, David; Labbe, Ivo; Tomczak, Adam; Allen, Rebecca; Alcorn, Leo

    2016-09-01

    We present an overview and the first data release of ZFIRE, a spectroscopic redshift survey of star-forming galaxies that utilizes the MOSFIRE instrument on Keck-I to study galaxy properties in rich environments at 1.5 < z < 2.5. ZFIRE measures accurate spectroscopic redshifts and basic galaxy properties derived from multiple emission lines. The galaxies are selected from a stellar mass limited sample based on deep near infrared imaging ({K}{AB}\\lt 25) and precise photometric redshifts from the ZFOURGE and UKIDSS surveys as well as grism redshifts from 3DHST. Between 2013 and 2015, ZFIRE has observed the COSMOS and UDS legacy fields over 13 nights and has obtained 211 galaxy redshifts over 1.57 < z < 2.66 from a combination of nebular emission lines (such as Hα, [N ii], Hβ, [O ii], [O iii], and [S ii]) observed at 1–2 μm. Based on our medium-band near infrared photometry, we are able to spectrophotometrically flux calibrate our spectra to ˜10% accuracy. ZFIRE reaches 5σ emission line flux limits of ˜3 × 10‑18 erg s‑1 cm‑2 with a resolving power of R = 3500 and reaches masses down to ˜109 M ⊙. We confirm that the primary input survey, ZFOURGE, has produced photometric redshifts for star-forming galaxies (including highly attenuated ones) accurate to {{Δ }}z/(1+{z}{spec})=0.015 with 0.7% outliers. We measure a slight redshift bias of <0.001, and we note that the redshift bias tends to be larger at higher masses. We also examine the role of redshift on the derivation of rest-frame colors and stellar population parameters from SED fitting techniques. The ZFIRE survey extends spectroscopically confirmed z ˜ 2 samples across a richer range of environments, here we make available the first public release of the data for use by the community.7

  12. ZFIRE: A KECK/MOSFIRE Spectroscopic Survey of Galaxies in Rich Environments at z ˜ 2

    NASA Astrophysics Data System (ADS)

    Nanayakkara, Themiya; Glazebrook, Karl; Kacprzak, Glenn G.; Yuan, Tiantian; Tran, Kim-Vy; Spitler, Lee; Kewley, Lisa; Straatman, Caroline; Cowley, Michael; Fisher, David; Labbe, Ivo; Tomczak, Adam; Allen, Rebecca; Alcorn, Leo

    2016-09-01

    We present an overview and the first data release of ZFIRE, a spectroscopic redshift survey of star-forming galaxies that utilizes the MOSFIRE instrument on Keck-I to study galaxy properties in rich environments at 1.5 < z < 2.5. ZFIRE measures accurate spectroscopic redshifts and basic galaxy properties derived from multiple emission lines. The galaxies are selected from a stellar mass limited sample based on deep near infrared imaging ({K}{AB}\\lt 25) and precise photometric redshifts from the ZFOURGE and UKIDSS surveys as well as grism redshifts from 3DHST. Between 2013 and 2015, ZFIRE has observed the COSMOS and UDS legacy fields over 13 nights and has obtained 211 galaxy redshifts over 1.57 < z < 2.66 from a combination of nebular emission lines (such as Hα, [N ii], Hβ, [O ii], [O iii], and [S ii]) observed at 1-2 μm. Based on our medium-band near infrared photometry, we are able to spectrophotometrically flux calibrate our spectra to ˜10% accuracy. ZFIRE reaches 5σ emission line flux limits of ˜3 × 10-18 erg s-1 cm-2 with a resolving power of R = 3500 and reaches masses down to ˜109 M ⊙. We confirm that the primary input survey, ZFOURGE, has produced photometric redshifts for star-forming galaxies (including highly attenuated ones) accurate to {{Δ }}z/(1+{z}{spec})=0.015 with 0.7% outliers. We measure a slight redshift bias of <0.001, and we note that the redshift bias tends to be larger at higher masses. We also examine the role of redshift on the derivation of rest-frame colors and stellar population parameters from SED fitting techniques. The ZFIRE survey extends spectroscopically confirmed z ˜ 2 samples across a richer range of environments, here we make available the first public release of the data for use by the community.7

  13. CHILES Con Pol: An ultra-deep JVLA survey probing galaxy evolution and cosmic magnetism

    NASA Astrophysics Data System (ADS)

    Hales, Christopher A.; Momjian, Emmanuel; van Gorkom, Jacqueline; Rupen, Michael P.; Greiner, Maksim; Ensslin, Torsten A.; Bonzini, Margherita; Padovani, Paolo; Harrison, Ian; Brown, Michael L.; Gim, Hansung; Yun, Min S.; Maddox, Natasha; Stewart, Adam; Fender, Rob P.; Tremou, Evangelia; Chomiuk, Laura; Peters, Charee; Wilcots, Eric M.; Lazio, Joseph

    2015-08-01

    We are undertaking a 1000 hour campaign with the Karl G. Jansky VLA to survey 0.2 square degrees of the COSMOS field in full polarization continuum at 1.4 GHz. Our observations are part of a joint program with the spectral line COSMOS HI Large Extragalactic Survey (CHILES). When complete, we expect our CHILES Continuum Polarization (CHILES Con Pol) survey to reach an SKA-era sensitivity of 500 nJy per 4 arcsecond resolving beam, the deepest view of the radio sky yet. CHILES Con Pol will open new and fertile parameter space, with sensitivity to star formation rates of 10 Msun per year out to an unprecedented redshift of z=2, and ultra-luminous infrared galaxies and sub-millimeter galaxies out to redshifts of z=8 and beyond. This rich resource will extend the utility of radio band studies beyond the usual radio quasar and radio galaxy populations, opening sensitivity to the starforming and radio-quiet AGN populations that form the bulk of extragalactic sources detected in the optical, X-ray, and infrared bands. In this talk I will outline the key science of CHILES Con Pol, including galaxy evolution and novel measurements of intergalactic magnetic fields. I will present initial results from the first 180 hours of the survey and describe our forthcoming Data Release 1. I invite the astronomical community to consider unique science that can be pursued with CHILES Con Pol radio data.

  14. THE ADVANCED CAMERA FOR SURVEYS NEARBY GALAXY SURVEY TREASURY. IV. THE STAR FORMATION HISTORY OF NGC 2976

    SciTech Connect

    Williams, Benjamin F.; Dalcanton, Julianne J.; Stilp, Adrienne; Gilbert, Karoline M.; Roskar, Rok; Gogarten, Stephanie M.; Seth, Anil C.; Weisz, Daniel; Skillman, Evan; Dolphin, Andrew; Holtzman, Jon E-mail: jd@astro.washington.ed E-mail: stephanie@astro.washington.ed E-mail: dweisz@astro.umn.ed E-mail: dolphin@raytheon.co

    2010-01-20

    We present resolved stellar photometry of NGC 2976 obtained with the Advanced Camera for Surveys (ACS) as part of the ACS Nearby Galaxy Survey Treasury (ANGST) program. The data cover the radial extent of the major axis of the disk out to 6 kpc, or approx6 scale lengths. The outer disk was imaged to a depth of M{sub F606W} approx 1, and an inner field was imaged to the crowding limit at a depth of M{sub F606W} approx -1. Through detailed analysis and modeling of the resulting color-magnitude diagrams, we have reconstructed the star formation history (SFH) of the stellar populations currently residing in these portions of the galaxy, finding similar ancient populations at all radii but significantly different young populations at increasing radii. In particular, outside of the well-measured break in the disk surface brightness profile, the age of the youngest population increases with distance from the galaxy center, suggesting that star formation is shutting down from the outside-in. We use our measured SFH, along with H I surface density measurements, to reconstruct the surface density profile of the disk during previous epochs. Comparisons between the recovered star formation rates and reconstructed gas densities at previous epochs are consistent with star formation following the Schmidt law during the past 0.5 Gyr, but with a drop in star formation efficiency at low gas densities, as seen in local galaxies at the present day. The current rate and gas density suggest that rapid star formation in NGC 2976 is currently in the process of ceasing from the outside-in due to gas depletion. This process of outer disk gas depletion and inner disk star formation was likely triggered by an interaction with the core of the M81 group approx>1 Gyr ago that stripped the gas from the galaxy halo and/or triggered gas inflow from the outer disk toward the galaxy center.

  15. Dissecting galaxy triplets in the Sloan Digital Sky Survey Data Release 10 - I. Stellar populations and emission line analysis

    NASA Astrophysics Data System (ADS)

    Costa-Duarte, M. V.; O'Mill, A. L.; Duplancic, F.; Sodré, L.; Lambas, D. G.

    2016-07-01

    We identify isolated galaxy triplets in a volume-limited sample from the Sloan Digital Sky Survey Data Release 10. Our final sample has 80 galaxy systems in the redshift range 0.04 ≤ z ≤ 0.1, brighter than Mr = -20.5 + 5 log h70. Spectral synthesis results and WHAN and BPT diagnostic diagrams were employed to classify the galaxies in these systems as star-forming, active nuclei, or passive/retired. Our results suggest that the brightest galaxies drive the triplet evolution, as evidenced by the strong correlations between properties as mass assembly and mean stellar population age with triplet properties. Galaxies with intermediate luminosity or the faintest one within the triplet seem to play a secondary role. Moreover, the relation between age and stellar mass of galaxies is similar for these galaxies but different for the brightest galaxy in the system. Most of the triplet galaxies are passive or retired, according to the WHAN classification. Low-mass triplets present different fractions of WHAN classes when compared to higher mass triplets. A census of WHAN class combinations shows the dominance of star-forming galaxies in low-mass triplets while retired and passive galaxies prevail in high-mass systems. We argue that these results suggest that the local environment, through galaxy interactions driven by the brightest galaxy, is playing a major role in triplet evolution.

  16. Trident: A three-pronged galaxy survey. I. Lyman alpha emitting galaxies at z ~ 2 in GOODS North

    NASA Astrophysics Data System (ADS)

    Sandberg, A.; Guaita, L.; Östlin, G.; Hayes, M.; Kiaeerad, F.

    2015-08-01

    Context. Lyman alpha (Lyα) emitting galaxies (LAEs) are used to probe the distant universe and are therefore important for galaxy evolution studies and for providing clues to the nature of the epoch of reionization. However, the exact circumstances under which Lyα escapes a galaxy are still not fully understood. Aims: The Trident project is designed to simultaneously examine Lyα, Hα, and Lyman continuum emission from galaxies at redshift z ~ 2, thus linking these three aspects of ionizing radiation in galaxies. In this paper, we outline the strategy of this project and examine the properties of LAEs in the GOODS North field. Methods: We performed a narrowband LAE survey in GOODS North using existing filters and two custom made filters at the Nordic Optical Telescope with MOSCA. We use complementary broadband archival data in the field to make a careful candidate selection and perform optical to near-IR SED fitting. We also estimate far-IR luminosities by matching our candidates to detections in Spitzer/MIPS 24 μm and Herschel/PACS catalogues. Results: We find a total of 25 LAE candidates, probing mainly the bright end of the LAE luminosity function with LLyα ~ 1-15 × 1042 erg s-1. They display a range of masses of ~ 0.5-50 × 109M⊙, and average ages from a few tens of Myr to 1 Gyr when assuming a constant star formation history. The majority of our candidates also show signs of recent elevated star formation. Three candidates have counterparts in the GOODS-Herschel far-IR catalogue, with luminosities consistent with ultra-luminous infrared galaxies (ULIRGs). Conclusions: The wide range of parameters derived from our SED fitting, as well as part of our sample being detected as ULIRGs, seems to indicate that at these Lyα luminosities, LAEs do not necessarily have to be young dwarfs, and that a lack of dust is not required for Lyα to escape. Based on observations made with the Nordic Optical Telescope, operated by the Nordic Optical Telescope Scientific

  17. The 6dF Galaxy Survey: the near-infrared Fundamental Plane of early-type galaxies

    NASA Astrophysics Data System (ADS)

    Magoulas, Christina; Springob, Christopher M.; Colless, Matthew; Jones, D. Heath; Campbell, Lachlan A.; Lucey, John R.; Mould, Jeremy; Jarrett, Tom; Merson, Alex; Brough, Sarah

    2012-11-01

    We determine the near-infrared Fundamental Plane (FP) for ˜104 early-type galaxies in the 6-degree Field Galaxy Survey (6dFGS). We fit the distribution of central velocity dispersion, near-infrared surface brightness and half-light radius with a 3D Gaussian model using a maximum-likelihood method. The model provides an excellent empirical fit to the observed FP distribution and the method proves robust and unbiased. Tests using simulations show that it gives superior results to regression techniques in the presence of significant and correlated uncertainties in all three parameters, censoring of the data by various selection effects and outliers in the data sample. For the 6dFGS J-band sample we find an FP with Re ∝ σ01.52±0.03Ie-0.89±0.01, similar to previous near-infrared determinations and consistent with the H- and K-band FPs once allowance is made for differences in mean colour. The overall scatter in Re about the FP is σr = 29 per cent, and is the quadrature sum of an 18 per cent scatter due to observational errors and a 23 per cent intrinsic scatter. Because of the Gaussian distribution of galaxies in FP space, σr is not the distance error, which we find to be σd = 23 per cent. Using group richness and local density as measures of environment, and morphologies based on visual classifications, we find that the FP slopes do not vary with environment or morphology. However, for fixed velocity dispersion and surface brightness, field galaxies are on average 5 per cent larger than galaxies in groups or higher density environments, and the bulges of early-type spirals are on average 10 per cent larger than ellipticals and lenticulars. The residuals about the FP show significant trends with environment, morphology and stellar population. The strongest trend is with age, and we speculate that age is the most important systematic source of offsets from the FP, and may drive the other trends through its correlations with environment, morphology and

  18. Populating dark matter haloes with galaxies: comparing the 2dFGRS with mock galaxy redshift surveys

    NASA Astrophysics Data System (ADS)

    Yang, Xiaohu; Mo, H. J.; Jing, Y. P.; van den Bosch, Frank C.; Chu, YaoQuan

    2004-06-01

    In two recent papers, we developed a powerful technique to link the distribution of galaxies to that of dark matter haloes by considering halo occupation numbers as a function of galaxy luminosity and type. In this paper we use these distribution functions to populate dark matter haloes in high-resolution N-body simulations of the standard ΛCDM cosmology with Ωm= 0.3, ΩΛ= 0.7 and σ8= 0.9. Stacking simulation boxes of 100 h-1 Mpc and 300 h-1 Mpc with 5123 particles each we construct mock galaxy redshift surveys out to a redshift of z= 0.2 with a numerical resolution that guarantees completeness down to 0.01L*. We use these mock surveys to investigate various clustering statistics. The predicted two-dimensional correlation function ξ(rp, π) reveals clear signatures of redshift space distortions. The projected correlation functions for galaxies with different luminosities and types, derived from ξ(rp, π), match the observations well on scales larger than ~3 h-1 Mpc. On smaller scales, however, the model overpredicts the clustering power by about a factor two. Modelling the `finger-of-God' effect on small scales reveals that the standard ΛCDM model predicts pairwise velocity dispersions (PVD) that are ~400 km s-1 too high at projected pair separations of ~1 h-1 Mpc. A strong velocity bias in massive haloes, with bvel≡σgal/σdm~ 0.6 (where σgal and σdm are the velocity dispersions of galaxies and dark matter particles, respectively) can reduce the predicted PVD to the observed level, but does not help to resolve the overprediction of clustering power on small scales. Consistent results can be obtained within the standard ΛCDM model only when the average mass-to-light ratio of clusters is of the order of 1000 (M/L)solar in the B-band. Alternatively, as we show by a simple approximation, a ΛCDM model with σ8~= 0.75 may also reproduce the observational results. We discuss our results in light of the recent WMAP results and the constraints on σ8 obtained

  19. Local starburst galaxies and their descendants. Statistics from the Sloan Digital Sky Survey

    NASA Astrophysics Data System (ADS)

    Bergvall, Nils; Marquart, Thomas; Way, Michael J.; Blomqvist, Anna; Holst, Emma; Östlin, Göran; Zackrisson, Erik

    2016-03-01

    Aims: Despite strong interest in the starburst phenomenon in extragalactic astronomy, the concept remains ill-defined. Here we use a strict definition of starburst to examine the statistical properties of starburst galaxies in the local universe. We also seek to establish links between starburst galaxies, post-starburst (hereafter postburst) galaxies, and active galaxies. Methods: Data were selected from the Sloan Digital Sky Survey DR7. We applied a novel method of treating dust attenuation and derive star formation rates, ages, and stellar masses assuming a two-component stellar population model. Dynamical masses are calculated from the width of the Hα line. These masses agree excellently with the photometric masses. The mass (gas+stars) range is ~109-1011.5ℳ⊙. As a selection criterion for starburst galaxies, we use, the birthrate parameter, b = SFR/ ⟨ SFR ⟩, requiring that b ≥ 3. For postburst galaxies, we use, the equivalent width of Hδ in absorption with the criterion EWHδ,abs ≥ 6 Å. Results: We find that only 1% of star-forming galaxies are starburst galaxies. They contribute 3-6% to the stellar production and are therefore unimportant for the local star formation activity. The median starburst age is 70 Myr roughly independent of mass, indicating that star formation is mainly regulated by local feedback processes. The b-parameter strongly depends on burst age. Values close to b = 60 are found at ages ~10 Myr, while almost no starbursts are found at ages >1 Gyr. The median baryonic burst mass fraction of sub-L∗ galaxies is 5% and decreases slowly towards high masses. The median mass fraction of the recent burst in the postburst sample is 5-10%. A smaller fraction of the postburst galaxies, however, originates in non-bursting galaxies. The age-mass distribution of the postburst progenitors (with mass fractions >3%) is bimodal with a break at logℳ(ℳ⊙) ~ 10.6, above which the ages are doubled. The starburst and postburst luminosity

  20. The REFLEX II galaxy cluster survey: power spectrum analysis

    NASA Astrophysics Data System (ADS)

    Balaguera-Antolínez, A.; Sánchez, Ariel G.; Böhringer, H.; Collins, C.; Guzzo, L.; Phleps, S.

    2011-05-01

    We present the power spectrum of galaxy clusters measured from the new ROSAT-ESO Flux-Limited X-Ray (REFLEX II) galaxy cluster catalogue. This new sample extends the flux limit of the original REFLEX catalogue to 1.8 × 10-12 erg s-1 cm-2, yielding a total of 911 clusters with ≥94 per cent completeness in redshift follow-up. The analysis of the data is improved by creating a set of 100 REFLEX II-catalogue-like mock galaxy cluster catalogues built from a suite of large-volume Λ cold dark matter (ΛCDM) N-body simulations (L-BASICC II). The measured power spectrum is in agreement with the predictions from a ΛCDM cosmological model. The measurements show the expected increase in the amplitude of the power spectrum with increasing X-ray luminosity. On large scales, we show that the shape of the measured power spectrum is compatible with a scale-independent bias and provide a model for the amplitude that allows us to connect our measurements with a cosmological model. By implementing a luminosity-dependent power-spectrum estimator, we observe that the power spectrum measured from the REFLEX II sample is weakly affected by flux-selection effects. The shape of the measured power spectrum is compatible with a featureless power spectrum on scales k > 0.01 h Mpc-1 and hence no statistically significant signal of baryonic acoustic oscillations can be detected. We show that the measured REFLEX II power spectrum displays signatures of non-linear evolution.

  1. New active galactic nuclei detected in ROSAT All Sky Survey galaxies. II. The complete dataset

    NASA Astrophysics Data System (ADS)

    Kollatschny, W.; Kotulla, R.; Pietsch, W.; Bischoff, K.; Zetzl, M.

    2008-06-01

    Aims: The ROSAT ALL Sky Survey Bright Source Catalogue (RASS-BSC) has been correlated with the Catalogue of Principal Galaxies (PGC) to identify new extragalactic counterparts. 550 reliable optical counterparts have been detected. However there existed no optical spectra for about 200 Active Galactic Nuclei (AGN) candidates before the ROSAT ALL Sky Survey (RASS) was completed. Methods: We took optical spectra of 176 X-ray candidates and companions at ESO, Calar Alto observatory and McDonald observatory. When necessary we used a line profile decomposition to measure line fluxes, widths and centers to classify their type of activity. Results: We discuss the redshift-, linewidth-, as well as optical and X-ray luminosity distribution of our ROSAT selected sample. 139 galaxies of our 166 X-ray counterparts have been identified as AGN with 93 being Seyfert 1 galaxies (61%). Eighteen of them (20%) are Narrow Line Seyfert 1 galaxies. 34 X-ray candidates (21%) are LINERs and only eight candidates (5%) are Seyfert 2. The ratio of the number of Seyfert 1 galaxies to Seyfert 2 galaxies is about 11/1. Optical surveys result in ratios of 1/1.4. The high fraction of detected Seyfert 1 galaxies is explained by the sensitivity of the ROSAT to soft X-rays which are heavily absorbed in type 2 AGN. Two X-ray candidates are HII-galaxies and 25 candidates (15%) show no signs of spectral activity. The AGN in our RASS selected sample exhibit slightly higher optical luminosities (MB = (-20.71 ± 1.75) mag) and similar X-ray luminosities (log(LX [ erg s-1] ) = 42.9 ± 1.7) compared to other AGN surveys. The Hα line width distribution (FWHM) of our newly identified ROSAT AGN sample is similar to the line widths distribution based on SDSS AGN. However, our newly identified RASS AGN have rather reddish colors explaining why they have not been detected before in ultraviolet or blue excess surveys.

  2. Using Gamma Regression for Photometric Redshifts of Survey Galaxies

    NASA Astrophysics Data System (ADS)

    Elliott, J.; de Souza, R. S.; Krone-Martins, A.; Cameron, E.; Ishida, E. E. O.; Hilbe, J.

    Machine learning techniques offer a plethora of opportunities in tackling big data within the astronomical community. We present the set of Generalized Linear Models as a fast alternative for determining photometric redshifts of galaxies, a set of tools not commonly applied within astronomy, despite being widely used in other professions. With this technique, we achieve catastrophic outlier rates of the order of ˜ 1%, that can be achieved in a matter of seconds on large datasets of size ˜ 1,000,000. To make these techniques easily accessible to the astronomical community, we developed a set of libraries and tools that are publicly available.

  3. Galaxy populations in the 26 most massive galaxy clusters in the South Pole Telescope SPT-SZ survey

    NASA Astrophysics Data System (ADS)

    Zenteno, A.; Mohr, J. J.; Desai, S.; Stalder, B.; Saro, A.; Dietrich, J. P.; Bayliss, M.; Bocquet, S.; Chiu, I.; Gonzalez, A. H.; Gangkofner, C.; Gupta, N.; Hlavacek-Larrondo, J.; McDonald, M.; Reichardt, C.; Rest, A.

    2016-10-01

    We present a study of the optical properties of the 26 most massive galaxy clusters within the South Pole Telescope Sunyaev-Zel'dovich (SPT-SZ) 2500 deg2 survey spanning the redshift range 0.10 < z < 1.13. We measure the radial profiles, the luminosity functions (LFs), and the halo occupation numbers (HONs) using optical data of typical depth m* + 2. The stacked radial profiles are consistent with a Navarro-Frenk-White profile of concentration 2.84^{+0.40}_{-0.37} for the red sequence (RS) and 2.36^{+0.38}_{-0.35} for the total population. Stacking the data in multiple redshift bins shows slight redshift evolution in the concentration when both the total population is used, and when only RS galaxies are used (at 2.1σ and 2.8σ, respectively). The stacked LF shows a faint end slope α = -1.06^{+0.04}_{-0.03} for the total and α = -0.80^{+0.04}_{-0.03} for the RS population. The redshift evolution of m* is consistent with a passively evolving composite stellar population (CSP) model. Adopting the CSP model predictions, we explore the redshift evolution of the Schechter parameters α and φ*. We find α for the total population to be consistent with no evolution (0.3σ), and mildly significant evidence of evolution for the red galaxies (1.1-2.1σ). The data show that the density φ*/E2(z) decreases with redshift, in tension with the self-similar expectation at a 2.4σ level for the total population. The measured HON-mass relation has a lower normalization than previous low redshift studies. Finally, our data support HON redshift evolution at a 2.1σ level, with clusters at higher redshift containing fewer galaxies than their low-z counterparts.

  4. The SAMI Galaxy Survey: the link between angular momentum and optical morphology

    NASA Astrophysics Data System (ADS)

    Cortese, L.; Fogarty, L. M. R.; Bekki, K.; van de Sande, J.; Couch, W.; Catinella, B.; Colless, M.; Obreschkow, D.; Taranu, D.; Tescari, E.; Barat, D.; Bland-Hawthorn, J.; Bloom, J.; Bryant, J. J.; Cluver, M.; Croom, S. M.; Drinkwater, M. J.; d'Eugenio, F.; Konstantopoulos, I. S.; Lopez-Sanchez, A.; Mahajan, S.; Scott, N.; Tonini, C.; Wong, O. I.; Allen, J. T.; Brough, S.; Goodwin, M.; Green, A. W.; Ho, I.-T.; Kelvin, L. S.; Lawrence, J. S.; Lorente, N. P. F.; Medling, A. M.; Owers, M. S.; Richards, S.; Sharp, R.; Sweet, S. M.

    2016-11-01

    We investigate the relationship between stellar and gas specific angular momentum j, stellar mass M* and optical morphology for a sample of 488 galaxies extracted from the Sydney-AAO Multi-object Integral field Galaxy Survey. We find that j, measured within one effective radius, monotonically increases with M* and that, for M* > 109.5 M⊙, the scatter in this relation strongly correlates with optical morphology (i.e. visual classification and Sérsic index). These findings confirm that massive galaxies of all types lie on a plane relating mass, angular momentum and stellar-light distribution, and suggest that the large-scale morphology of a galaxy is regulated by its mass and dynamical state. We show that the significant scatter in the M*-j relation is accounted for by the fact that, at fixed stellar mass, the contribution of ordered motions to the dynamical support of galaxies varies by at least a factor of 3. Indeed, the stellar spin parameter (quantified via λR) correlates strongly with Sérsic and concentration indices. This correlation is particularly strong once slow rotators are removed from the sample, showing that late-type galaxies and early-type fast rotators form a continuous class of objects in terms of their kinematic properties.

  5. What have we learned from the XMM-Newton surveys of Local Group Galaxies?

    NASA Astrophysics Data System (ADS)

    Haberl, F.

    2016-06-01

    The study of X-ray source populations and diffuse X-ray emission in nearby galaxies is of major importance in understanding the X-ray output of more distant galaxies as well as learning about processes that occur on interstellar scales within our own Galaxy. Depending on the star formation history of the galaxies different types of X-ray sources dominate the total X-ray emission. With modern observatories like XMM-Newton the various classes of X-ray sources (high and low mass X-ray binaries, supernova remnants, super-soft sources) can be studied to the faintest end of their luminosity distribution in Local Group galaxies. XMM-Newton successfully surveyed the large spiral galaxies M31 and M33 and the star forming, irregular Magellanic Clouds. I'll summarise the most important results we have obtained from older populations like low mass X-ray binaries and classical novae in M31 to the younger populations of high mass X-ray binaries and supernova remnants in the Magellanic Clouds. I'll discuss still open questions in this field of research which can be addressed using the high sensitivity of the XMM-Newton instruments.

  6. The Hawaii K-band galaxy survey. 1: Deep K-band imaging

    NASA Technical Reports Server (NTRS)

    Cowie, L. L.; Gardner, J. P.; Hu, E. M.; Songaila, A.; Hodapp, K.-W.; Wainscoat, R. J.

    1994-01-01

    We present the results of a very deep K-band survey with a 5 sigma total galaxy magnitude limit of K = 21.9 in the deepest field. A 5 sigma K-band-selected sample of 123 galaxies is presented, together with their optical colors. Only three galaxies in this sample are not detected at the 1 sigma level in Kron-Cousins I band. At K less than or = 20 the reddest (I-K) color is 5.1 +/- 0.4, and 15 of the 123 objects in the deep field sample have (I-K) greater than 4. In the blue, the galaxies show a rapid blueward trend at magnitudes beyond K = 19, dropping from a median (B-K) = 6 at K = 18 to a median (B-K) of only 4.2 at K = 21.5. The surface density of (I-K) greater than 4 objects is interpreted to imply either that there is a significant evolution toward later types in the colors of the normal galaxy population beyond z = 11 or that galaxies have faded by that redshift.

  7. Bar properties as seen in the Spitzer Survey of Stellar Structure in Galaxies

    NASA Astrophysics Data System (ADS)

    Sheth, Kartik

    2015-03-01

    Bars serve a crucial signpost in galaxy evolution because they form quickly once a disk is sufficiently massive and dynamically cold. Although the bar fraction in the local Universe is well-established since the mid-60s, a variety of studies have concluded varying bar fractions due to different definitions of bars, use of low quality data or different sample selection. The Spitzer Survey of Stellar Structure in Galaxies (S4G) offers us the ideal data set for resolving this outstanding issue once and for all. S4G consists of over 2000 nearby galaxies chosen based on optical brightness, distance, galactic latitude and size in a 40 Mpc volume. With a 4 minute integration time per pixel over >1.5 × D25 diameter for each galaxy, the data provide the deepest, homogenous, mid-infrared (3.6 and 4.5 microns) data on the nearby Universe. The data are so deep that we are tracing stellar surface densities << 1 solar mass per square parsec. With these data we can confidently constrain the bar fraction and thus shed important light on the evolutionary state of galaxies as a function of mass, environment and other galaxy host properties.

  8. GESE: A Small UV Space Telescope to Conduct a Large Spectroscopic Survey of Z-1 Galaxies

    NASA Technical Reports Server (NTRS)

    Heap, Sara R.; Gong, Qian; Hull, Tony; Kruk, Jeffrey; Purves, Lloyd

    2013-01-01

    One of the key goals of NASA's astrophysics program is to answer the question: How did galaxies evolve into the spirals and elliptical galaxies that we see today? We describe a space mission concept called Galaxy Evolution Spectroscopic Explorer (GESE) to address this question by making a large spectroscopic survey of galaxies at a redshift, z is approximately 1 (look-back time of approximately 8 billion years). GESE is a 1.5-meter space telescope with an ultraviolet (UV) multi-object slit spectrograph that can obtain spectra of hundreds of galaxies per exposure. The spectrograph covers the spectral range, 0.2-0.4 micrometers at a spectral resolving power, R approximately 500. This observed spectral range corresponds to 0.1-0.2 micrometers as emitted by a galaxy at a redshift, z=1. The mission concept takes advantage of two new technological advances: (1) light-weighted, wide-field telescope mirrors, and (2) the Next- Generation MicroShutter Array (NG-MSA) to be used as a slit generator in the multi-object slit spectrograph.

  9. The SAMI Galaxy Survey: the link between angular momentum and optical morphology

    NASA Astrophysics Data System (ADS)

    Cortese, L.; Fogarty, L. M. R.; Bekki, K.; van de Sande, J.; Couch, W.; Catinella, B.; Colless, M.; Obreschkow, D.; Taranu, D.; Tescari, E.; Barat, D.; Bland-Hawthorn, J.; Bloom, J.; Bryant, J. J.; Cluver, M.; Croom, S. M.; Drinkwater, M. J.; d'Eugenio, F.; Konstantopoulos, I. S.; Lopez-Sanchez, A.; Mahajan, S.; Scott, N.; Tonini, C.; Wong, O. I.; Allen, J. T.; Brough, S.; Goodwin, M.; Green, A. W.; Ho, I.-T.; Kelvin, L. S.; Lawrence, J. S.; Lorente, N. P. F.; Medling, A. M.; Owers, M. S.; Richards, S.; Sharp, R.; Sweet, S. M.

    2016-08-01

    We investigate the relationship between stellar and gas specific angular momentum j, stellar mass M★ and optical morphology for a sample of 488 galaxies extracted from the SAMI Galaxy Survey. We find that j, measured within one effective radius, monotonically increases with M★ and that, for M★ > 109.5 M⊙, the scatter in this relation strongly correlates with optical morphology (i.e., visual classification and Sérsic index). These findings confirm that massive galaxies of all types lie on a plane relating mass, angular momentum and stellar light distribution, and suggest that the large-scale morphology of a galaxy is regulated by its mass and dynamical state. We show that the significant scatter in the M★ - j relation is accounted for by the fact that, at fixed stellar mass, the contribution of ordered motions to the dynamical support of galaxies varies by at least a factor of three. Indeed, the stellar spin parameter (quantified via λR) correlates strongly with Sérsic and concentration indices. This correlation is particularly strong once slow-rotators are removed from the sample, showing that late-type galaxies and early-type fast rotators form a continuous class of objects in terms of their kinematic properties.

  10. Unveiling a Rich System of Faint Dwarf Galaxies in the Next Generation Fornax Survey

    NASA Astrophysics Data System (ADS)

    Muñoz, Roberto P.; Eigenthaler, Paul; Puzia, Thomas H.; Taylor, Matthew A.; Ordenes-Briceño, Yasna; Alamo-Martínez, Karla; Ribbeck, Karen X.; Ángel, Simón; Capaccioli, Massimo; Côté, Patrick; Ferrarese, Laura; Galaz, Gaspar; Hempel, Maren; Hilker, Michael; Jordán, Andrés; Lançon, Ariane; Mieske, Steffen; Paolillo, Maurizio; Richtler, Tom; Sánchez-Janssen, Ruben; Zhang, Hongxin

    2015-11-01

    We report the discovery of 158 previously undetected dwarf galaxies in the Fornax cluster central regions using a deep coadded u-, g-, and i-band image obtained with the Dark Energy Camera wide-field camera mounted on the 4-m Blanco telescope at the Cerro Tololo Interamerican Observatory as part of the Next Generation Fornax Survey (NGFS). The new dwarf galaxies have quasi-exponential light profiles, effective radii 0.1 < re < 2.8 kpc, and average effective surface brightness values 22.0 < μi < 28.0 mag arcsec-2. We confirm the existence of ultra-diffuse galaxies (UDGs) in the Fornax core regions that resemble counterparts recently discovered in the Virgo and Coma galaxy clusters. We also find extremely low surface brightness NGFS dwarfs, which are several magnitudes fainter than the classical UDGs. The faintest dwarf candidate in our NGFS sample has an absolute magnitude of Mi = -8.0 mag. The nucleation fraction of the NGFS dwarf galaxy sample appears to decrease as a function of their total luminosity, reaching from a nucleation fraction of >75% at luminosities brighter than Mi ≃ -15.0 mag to 0% at luminosities fainter than Mi ≃ -10.0 mag. The two-point correlation function analysis of the NGFS dwarf sample shows an excess on length scales below ˜100 kpc, pointing to the clustering of dwarf galaxies in the Fornax cluster core.

  11. Low Mass Galaxy Evolution In The WFC3 Infrared Spectroscopic Parallels Survey

    NASA Astrophysics Data System (ADS)

    Colbert, James; Teplitz, Harry; Scarlata, Claudia; Siana, Brian; Malkan, Matt; McCarthy, Patrick; Henry, Alaina; Atek, Hakim; Fosbury, Robert; Ross, Nathanial; Hathi, Nimish; Bridge, Carrie; Bunker, Andrew; Dressler, Alan; Shim, Hyunjin; Bedregal, Alejandro; Dominguez, Alberto; Rafelski, Marc; Masters, Dan

    2012-12-01

    The WFC3 Infrared Spectroscopic Parallel (WISP) Survey uses nearly 1000 HST orbits to study the epoch of peak star formation. Its slitless grism spectroscopy over a wide, continuous spectral range (0.8-1.7 micron) provides an unbiased selection of thousands of emission line galaxies over 0.5 < z < 2.5. Hundreds of these galaxies are detected in multiple emission lines, allowing for important diagnostics of metallicity and dust extinction. We propose deep 3.6 micron imaging (5 sigma, 0.9 micro-Jy) of 39 of the deepest WISP fields observed with the combination of G102+G141 grisms, in order to detect emission-line galaxies down to 0.1 L*. Combined with our HST optical and near-IR photometry, these IRAC data will be critical to determining accurate stellar masses for both passive and active galaxies in our survey. We will determine the evolution of the faint end slope of the stellar mass function and the mass-metallicity relation down to low-mass galaxies, including measurement of a possible mass-metallicity-SFR fundamental plane. The addition of the IRAC photometry will also provide much stronger constraints on dust extinction and star formation history, especially when combined with information available from the emission lines themselves.

  12. Star/galaxy separation at faint magnitudes: Application to a simulated Dark Energy Survey

    SciTech Connect

    Soumagnac, M.T.; et al.

    2013-06-21

    We address the problem of separating stars from galaxies in future large photometric surveys. We focus our analysis on simulations of the Dark Energy Survey (DES). In the first part of the paper, we derive the science requirements on star/galaxy separation, for measurement of the cosmological parameters with the Gravitational Weak Lensing and Large Scale Structure probes. These requirements are dictated by the need to control both the statistical and systematic errors on the cosmological parameters, and by Point Spread Function calibration. We formulate the requirements in terms of the completeness and purity provided by a given star/galaxy classifier. In order to achieve these requirements at faint magnitudes, we propose a new method for star/galaxy separation in the second part of the paper. We first use Principal Component Analysis to outline the correlations between the objects parameters and extract from it the most relevant information. We then use the reduced set of parameters as input to an Artificial Neural Network. This multi-parameter approach improves upon purely morphometric classifiers (such as the classifier implemented in SExtractor), especially at faint magnitudes: it increases the purity by up to 20% for stars and by up to 12% for galaxies, at i-magnitude fainter than 23.

  13. The Brightest of Reionizing Galaxies Survey: A Protocluster Candidate at redshift z 8

    NASA Astrophysics Data System (ADS)

    Trenti, Michele; Collective, BoRG

    2012-01-01

    Theoretical and numerical modeling of dark-matter halo assembly predicts that the most luminous galaxies at high redshift are surrounded by overdensities of fainter companions. We test this prediction with HST observations acquired by our Brightest of Reionizing Galaxies (BoRG) survey, finding a correlation between counts of bright and faint candidate galaxies at z 8 which is significant at >99.8% confidence. Furthermore, the best z 8 bright candidate of the survey is associated to the most significant overdensity of faint galaxies (4 additional sources within a region of diameter 70arcsec, where only 0.2 where expected), indicating that we identified a candidate protocluster at confidence >99.99%. We modeled the overdensity by means of cosmological simulations and estimate that the principal dark matter halo has mass Mh (4-7)x1011Msun ( 5sigma density peak) and is surrounded by several Mh 1011Msun halos which could host the fainter dropouts. In this scenario, we predict that all halos will eventually merge into a Mh>2x1014Msun galaxy cluster by z=0. Follow-up observations with ground and space based telescopes are required to secure the z 8 nature of the overdensity, discover new members, and measure their precise redshift.

  14. The ACS Fornax Cluster Survey. XII. Diffuse Star Clusters in Early-type Galaxies

    NASA Astrophysics Data System (ADS)

    Liu, Yiqing; Peng, Eric W.; Lim, Sungsoon; Jordán, Andrés; Blakeslee, John; Côté, Patrick; Ferrarese, Laura; Pattarakijwanich, Petchara

    2016-10-01

    Diffuse star clusters (DSCs) are old and dynamically hot stellar systems that have lower surface brightness and more extended morphology than globular clusters (GCs). Using the images from Hubble Space Telescope (HST)/ACS Fornax Cluster Survey, we find that 12 out of 43 early-type galaxies (ETGs) in the Fornax Cluster host significant numbers of DSCs. Together with literature data from the HST/ACS Virgo Cluster Survey, where 18 out of 100 ETGs were found to host DSCs, we systematically study the relationship of DSCs with GCs and their host galaxy environment. Two DSC hosts are post-merger galaxies, with most of the other hosts either having low mass or showing clear disk components. We find that while the number ratio of DSCs to GCs is nearly constant in massive galaxies, the DSC-to-GC ratio becomes systematically higher in lower-mass hosts. This suggests that DSCs may be more efficient at forming (or surviving) in low-density environments. DSC hosts are not special either in their position in the cluster or in the galactic color–magnitude diagram. Why some disk and low-mass galaxies host DSCs while others do not is still a puzzle, however. The mean ages of DSC hosts and nonhosts are similar at similar masses, implying that formation efficiency rather than survival is the reason behind different DSC number fractions in ETGs.

  15. H I-SELECTED GALAXIES IN THE SLOAN DIGITAL SKY SURVEY. I. OPTICAL DATA

    SciTech Connect

    West, Andrew A.; Garcia-Appadoo, Diego A.; Dalcanton, Julianne J.; Ivezic, Zeljko; Bentz, Misty C.; Disney, Mike J.; Rockosi, Constance M.

    2010-02-15

    We present the optical data for 195 H I-selected galaxies that fall within both the Sloan Digital Sky Survey (SDSS) and the Parkes Equatorial Survey (ES). The photometric quantities have been independently recomputed for our sample using a new photometric pipeline optimized for large galaxies, thus correcting for SDSS's limited reliability for automatic photometry of angularly large or low surface brightness (LSB) galaxies. We outline the magnitude of the uncertainty in the SDSS catalog-level photometry and derive a quantitative method for correcting the over-sky subtraction in the SDSS photometric pipeline. The main thrust of this paper is to present the ES/SDSS sample and discuss the methods behind the improved photometry, which will be used in future scientific analysis. We present the overall optical properties of the sample and briefly compare to a volume-limited, optically selected sample. Compared to the optically selected SDSS sample (in the similar volume), H I-selected galaxies are bluer and more luminous (fewer dwarf ellipticals and more star formation). However, compared to typical SDSS galaxy studies, which have their own selection effect, our sample is bluer, fainter, and less massive.

  16. PHYSICAL AND MORPHOLOGICAL PROPERTIES OF [O II] EMITTING GALAXIES IN THE HETDEX PILOT SURVEY

    SciTech Connect

    Bridge, Joanna S.; Gronwall, Caryl; Ciardullo, Robin; Hagen, Alex; Zeimann, Greg; Malz, A. I.; Schneider, Donald P. E-mail: caryl@astro.psu.edu E-mail: hagen@psu.edu E-mail: aimalz@psu.edu; and others

    2015-02-01

    The Hobby-Eberly Dark Energy Experiment pilot survey identified 284 [O II] λ3727 emitting galaxies in a 169 arcmin{sup 2} field of sky in the redshift range 0 < z < 0.57. This line flux limited sample provides a bridge between studies in the local universe and higher-redshift [O II] surveys. We present an analysis of the star formation rates (SFRs) of these galaxies as a function of stellar mass as determined via spectral energy distribution fitting. The [O II] emitters fall on the ''main sequence'' of star-forming galaxies with SFR decreasing at lower masses and redshifts. However, the slope of our relation is flatter than that found for most other samples, a result of the metallicity dependence of the [O II] star formation rate indicator. The mass-specific SFR is higher for lower mass objects, supporting the idea that massive galaxies formed more quickly and efficiently than their lower mass counterparts. This is confirmed by the fact that the equivalent widths of the [O II] emission lines trend smaller with larger stellar mass. Examination of the morphologies of the [O II] emitters reveals that their star formation is not a result of mergers, and the galaxies' half-light radii do not indicate evolution of physical sizes.

  17. Gravitational redshift of galaxies in clusters from the sloan digital sky survey and the Baryon Oscillation spectroscopic survey.

    PubMed

    Sadeh, Iftach; Feng, Low Lerh; Lahav, Ofer

    2015-02-20

    The gravitational redshift effect allows one to directly probe the gravitational potential in clusters of galaxies. Following up on Wojtak et al. [Nature (London) 477, 567 (2011)], we present a new measurement. We take advantage of new data from the tenth data release of the Sloan Digital Sky Survey and the Baryon Oscillation Spectroscopic Survey. We compare the spectroscopic redshift of the brightest cluster galaxies (BCGs) with that of galaxies at the outskirts of clusters, using a sample with an average cluster mass of 1014M⊙. We find that these galaxies have an average relative redshift of -11  km/s compared with that of BCGs, with a standard deviation of +7 and -5  km/s. Our measurement is consistent with that of Wojtak et al. [Nature (London) 477, 567 (2011)]. However, our derived standard deviation is larger, as we take into account various systematic effects, beyond the size of the data set. The result is in good agreement with the predictions from general relativity.

  18. Gravitational Redshift of Galaxies in Clusters from the Sloan Digital Sky Survey and the Baryon Oscillation Spectroscopic Survey

    NASA Astrophysics Data System (ADS)

    Sadeh, Iftach; Feng, Low Lerh; Lahav, Ofer

    2015-02-01

    The gravitational redshift effect allows one to directly probe the gravitational potential in clusters of galaxies. Following up on Wojtak et al. [Nature (London) 477, 567 (2011)], we present a new measurement. We take advantage of new data from the tenth data release of the Sloan Digital Sky Survey and the Baryon Oscillation Spectroscopic Survey. We compare the spectroscopic redshift of the brightest cluster galaxies (BCGs) with that of galaxies at the outskirts of clusters, using a sample with an average cluster mass of 1014 M⊙ . We find that these galaxies have an average relative redshift of -11 km /s compared with that of BCGs, with a standard deviation of +7 and -5 km /s . Our measurement is consistent with that of Wojtak et al. [Nature (London) 477, 567 (2011)]. However, our derived standard deviation is larger, as we take into account various systematic effects, beyond the size of the data set. The result is in good agreement with the predictions from general relativity.

  19. Gravitational redshift of galaxies in clusters from the sloan digital sky survey and the Baryon Oscillation spectroscopic survey.

    PubMed

    Sadeh, Iftach; Feng, Low Lerh; Lahav, Ofer

    2015-02-20

    The gravitational redshift effect allows one to directly probe the gravitational potential in clusters of galaxies. Following up on Wojtak et al. [Nature (London) 477, 567 (2011)], we present a new measurement. We take advantage of new data from the tenth data release of the Sloan Digital Sky Survey and the Baryon Oscillation Spectroscopic Survey. We compare the spectroscopic redshift of the brightest cluster galaxies (BCGs) with that of galaxies at the outskirts of clusters, using a sample with an average cluster mass of 1014M⊙. We find that these galaxies have an average relative redshift of -11  km/s compared with that of BCGs, with a standard deviation of +7 and -5  km/s. Our measurement is consistent with that of Wojtak et al. [Nature (London) 477, 567 (2011)]. However, our derived standard deviation is larger, as we take into account various systematic effects, beyond the size of the data set. The result is in good agreement with the predictions from general relativity. PMID:25763947

  20. Solo dwarfs I: survey introduction and first results for the Sagittarius dwarf irregular galaxy

    NASA Astrophysics Data System (ADS)

    Higgs, C. R.; McConnachie, A. W.; Irwin, M.; Bate, N. F.; Lewis, G. F.; Walker, M. G.; Côté, P.; Venn, K.; Battaglia, G.

    2016-05-01

    We introduce the Solitary Local dwarfs survey (Solo), a wide-field photometric study targeting every isolated dwarf galaxy within 3 Mpc of the Milky Way. Solo is based on (u)gi multiband imaging from Canada-France-Hawaii Telescope/MegaCam for northern targets, and Magellan/Megacam for southern targets. All galaxies fainter than MV ≃ -18 situated beyond the nominal virial radius of the Milky Way and M31 (≳300 kpc) are included in this volume-limited sample, for a total of 42 targets. In addition to reviewing the survey goals and strategy, we present results for the Sagittarius dwarf irregular galaxy (Sag DIG), one of the most isolated, low-mass galaxies, located at the edge of the Local Group. We analyse its resolved stellar populations and their spatial distributions. We provide updated estimates of its central surface brightness and integrated luminosity, and trace its surface brightness profile to a level fainter than 30 mag arcsec-2. Sag DIG is well described by a highly elliptical (disc-like) system following a single component Sérsic model. However, a low-level distortion is present at the outer edges of the galaxy that, were Sag DIG not so isolated, would likely be attributed to some kind of previous tidal interaction. Further, we find evidence of an extremely low level, extended distribution of stars beyond ˜5 arcmin (>1.5 kpc) that suggests Sag DIG may be embedded in a very low-density stellar halo. We compare the stellar and H I structures of Sag DIG, and discuss results for this galaxy in relation to other isolated, dwarf irregular galaxies in the Local Group.

  1. The SLUGGS survey: wide-field stellar kinematics of early-type galaxies

    SciTech Connect

    Arnold, Jacob A.; Romanowsky, Aaron J.; Brodie, Jean P.; Woodley, Kristin A.; Forbes, Duncan A.; Blom, Christina; Kartha, Sreeja S.; Pastorello, Nicola; Pota, Vincenzo; Usher, Christopher; Strader, Jay; Spitler, Lee R.; Foster, Caroline

    2014-08-20

    We present stellar kinematics of 22 nearby early-type galaxies (ETGs), based on two-dimensional (2D) absorption line stellar spectroscopy out to ∼2-4 R {sub e} (effective radii), as part of the ongoing SLUGGS Survey. The galaxies span a factor of 20 in intrinsic luminosity, as well as a full range of environment and ETG morphology. Our data consist of good velocity resolution (σ{sub inst} ∼ 25 km s{sup –1}) integrated stellar-light spectra extracted from the individual slitlets of custom made Keck/DEIMOS slitmasks. We extract stellar kinematics measurements (V, σ, h {sub 3}, and h {sub 4}) for each galaxy. Combining with literature values from smaller radii, we present 2D spatially resolved maps of the large-scale kinematic structure in each galaxy. We find that the kinematic homogeneity found inside 1 R {sub e} often breaks down at larger radii, where a variety of kinematic behaviors are observed. While central slow rotators remain slowly rotating in their halos, central fast rotators show more diversity, ranging from rapidly increasing to rapidly declining specific angular momentum profiles in the outer regions. There are indications that the outer trends depend on morphological type, raising questions about the proposed unification of the elliptical and lenticular (S0) galaxy families in the ATLAS{sup 3D} survey. Several galaxies in our sample show multiple lines of evidence for distinct disk components embedded in more slowly rotating spheroids, and we suggest a joint photometric-kinematic approach for robust bulge-disk decomposition. Our observational results appear generally consistent with a picture of two-phase (in-situ plus accretion) galaxy formation.

  2. The COS-Dwarfs Survey: The Carbon Reservoir around Sub-L* Galaxies

    NASA Astrophysics Data System (ADS)

    Bordoloi, Rongmon; Tumlinson, Jason; Werk, Jessica K.; Oppenheimer, Benjamin D.; Peeples, Molly S.; Prochaska, J. Xavier; Tripp, Todd M.; Katz, Neal; Davé, Romeel; Fox, Andrew J.; Thom, Christopher; Ford, Amanda Brady; Weinberg, David H.; Burchett, Joseph N.; Kollmeier, Juna A.

    2014-12-01

    We report new observations of circumgalactic gas from the COS-Dwarfs survey, a systematic investigation of the gaseous halos around 43 low-mass z <= 0.1 galaxies using background QSOs observed with the Cosmic Origins Spectrograph. From the projected one-dimensional and two-dimensional distribution of C IV absorption, we find that C IV is detected out to ≈100 kpc (corresponding roughly to ≈0.5 R vir) of the host galaxies. The C IV absorption strength falls off radially as a power law, and beyond ≈0.5 R vir, no C IV absorption is detected above our sensitivity limit of ≈50-100 mÅ. We find a tentative correlation between detected C IV absorption strength and star formation, paralleling the strong correlation seen in highly ionized oxygen for L ~ L* galaxies by the COS-Halos survey. The data imply a large carbon reservoir in the circumgalactic medium (CGM) of these galaxies, corresponding to a minimum carbon mass of >~ 1.2 × 106 M ⊙ out to ~110 kpc. This mass is comparable to the carbon mass in the interstellar medium and exceeds the carbon mass currently in the stars of these galaxies. The C IV absorption seen around these sub-L* galaxies can account for almost two-thirds of all Wr >= 100 mÅ C IV absorption detected at low z. Comparing the C IV covering fraction with hydrodynamical simulations, we find that an energy-driven wind model is consistent with the observations whereas a wind model of constant velocity fails to reproduce the CGM or the galaxy properties. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program GO12248.

  3. COMPARING DENSE GALAXY CLUSTER REDSHIFT SURVEYS WITH WEAK-LENSING MAPS

    SciTech Connect

    Hwang, Ho Seong; Geller, Margaret J.; Zahid, H. Jabran; Diaferio, Antonaldo; Rines, Kenneth J. E-mail: mgeller@cfa.harvard.edu E-mail: diaferio@ph.unito.it

    2014-12-20

    We use dense redshift surveys of nine galaxy clusters at z ∼ 0.2 to compare the galaxy distribution in each system with the projected matter distribution from weak lensing. By combining 2087 new MMT/Hectospec redshifts and the data in the literature, we construct spectroscopic samples within the region of weak-lensing maps of high (70%-89%) and uniform completeness. With these dense redshift surveys, we construct galaxy number density maps using several galaxy subsamples. The shape of the main cluster concentration in the weak-lensing maps is similar to the global morphology of the number density maps based on cluster members alone, mainly dominated by red members. We cross-correlate the galaxy number density maps with the weak-lensing maps. The cross-correlation signal when we include foreground and background galaxies at 0.5z {sub cl} < z < 2z {sub cl} is 10%-23% larger than for cluster members alone at the cluster virial radius. The excess can be as high as 30% depending on the cluster. Cross-correlating the galaxy number density and weak-lensing maps suggests that superimposed structures close to the cluster in redshift space contribute more significantly to the excess cross-correlation signal than unrelated large-scale structure along the line of sight. Interestingly, the weak-lensing mass profiles are not well constrained for the clusters with the largest cross-correlation signal excesses (>20% for A383, A689, and A750). The fractional excess in the cross-correlation signal including foreground and background structures could be a useful proxy for assessing the reliability of weak-lensing cluster mass estimates.

  4. The Spitzer/Swift Gamma-Ray Burst Host Galaxy Legacy Survey

    NASA Astrophysics Data System (ADS)

    Perley, Daniel; Berger, Edo; Butler, Nathaniel; Cenko, S. Bradley; Chary, Ranga-Ram; Cucchiara, Antonino; Ellis, Richard; Fong, Wen-fai; Fruchter, Andrew; Fynbo, Johan; Gehrels, Neil; Graham, John; Greiner, Jochen; Hjorth, Jens; Hunt, Leslie; Jakobsson, Pall; Kruehler, Thomas; Laskar, Tanmoy; Le Floc'h, Emerich; Levan, Andrew; Levesque, Emily; Littlejohns, Owen; Malesani, Daniele; Michalowski, Michal; Milvang-Jensen, Bo; Prochaska, J. Xavier; Salvaterra, Ruben; Schulze, Steve; Schady, Patricia; Tanvir, Nial; de Ugarte Postigo, Antonio; Vergani, Susanna; Watson, Darach

    2016-08-01

    Long-duration gamma-ray bursts act as beacons to the sites of star-formation in the distant universe. GRBs reveal galaxies too faint and star-forming regions too dusty to characterize in detail using any other method, and provide a powerful independent constraint on the evolution of the cosmic star-formation rate density at high-redshift. However, a full understanding of the GRB phenomenon and its relation to cosmic star-formation requires connecting the observations obtained from GRBs to the properties of the galaxies hosting them. The large majority of GRBs originate at moderate to high redshift (z>1) and Spitzer has proven crucial for understanding the host population, given its unique ability to observe the rest-frame NIR and its unrivaled sensitivity and efficiency. We propose to complete a comprehensive public legacy survey of the Swift GRB host population to build on our earlier successes and push beyond the statistical limits of previous, smaller efforts. Our survey will enable a diverse range of GRB and galaxy science including: (1) to quantitatively and robustly map the connection between GRBs and cosmic star-formation to constrain the GRB progenitor and calibrate GRB rate-based measurements of the high-z cosmic star-formation rate; (2) to constrain the luminosity function of star-forming galaxies at the faint end and at high redshift; (3) to understand how the ISM properties seen in absorption in high-redshift galaxies unveiled by GRBs - metallicity, dust column, dust properties - connect to global properties of the host galaxies such as mass and age. Building on a decade of experience at both observatories, our observations will create an enduring joint Swift-Spitzer legacy sample - providing the definitive resource with which to examine all aspects of the GRB/galaxy connection for years to come and setting the stage for intensive JWST follow-up of the most interesting sources from our sample.

  5. Galaxy triplets in Sloan Digital Sky Survey Data Release 7 - I. Catalogue

    NASA Astrophysics Data System (ADS)

    O'Mill, Ana Laura; Duplancic, Fernanda; García Lambas, Diego; Valotto, Carlos; Sodré, Laerte

    2012-04-01

    We present a new catalogue of galaxy triplets derived from the Sloan Digital Sky Survey (SDSS) Data Release 7. The identification of systems was performed considering galaxies brighter than Mr=-20.5 and imposing constraints over the projected distances, radial velocity differences of neighbouring galaxies and isolation. To improve the identification of triplets, we employed a data pixelization scheme, which allows us to handle large amounts of data as in the SDSS photometric survey. Using spectroscopic and photometric data in the redshift range 0.01 ≤z≤ 0.40, we obtain 5901 triplet candidates. We have used a mock catalogue to analyse the completeness and contamination of our methods. The results show a high level of completeness (˜80 per cent) and low contamination (˜5 per cent). By using photometric and spectroscopic data, we have also addressed the effects of fibre collisions in the spectroscopic sample. We have defined an isolation criterion considering the distance of the triplet brightest galaxy to the closest neighbour cluster, to describe a global environment, as well as the galaxies within a fixed aperture, around the triplet brightest galaxy, to measure the local environment. The final catalogue comprises 1092 isolated triplets of galaxies in the redshift range 0.01 ≤z≤ 0.40. Our results show that photometric redshifts provide very useful information, allowing us to complete the sample of nearby systems whose detection is affected by fibre collisions, as well as extending the detection of triplets to large distances, where spectroscopic redshifts are not available.

  6. the COS-Dwarfs survey: the carbon reservoir around sub-L* galaxies

    SciTech Connect

    Bordoloi, Rongmon; Tumlinson, Jason; Peeples, Molly S.; Fox, Andrew J.; Thom, Christopher; Werk, Jessica K.; Prochaska, J. Xavier; Tripp, Todd M.; Katz, Neal; Burchett, Joseph N.; Davé, Romeel; Ford, Amanda Brady; Weinberg, David H.; Kollmeier, Juna A.

    2014-12-01

    We report new observations of circumgalactic gas from the COS-Dwarfs survey, a systematic investigation of the gaseous halos around 43 low-mass z ≤ 0.1 galaxies using background QSOs observed with the Cosmic Origins Spectrograph. From the projected one-dimensional and two-dimensional distribution of C IV absorption, we find that C IV is detected out to ≈100 kpc (corresponding roughly to ≈0.5 R {sub vir}) of the host galaxies. The C IV absorption strength falls off radially as a power law, and beyond ≈0.5 R {sub vir}, no C IV absorption is detected above our sensitivity limit of ≈50-100 mÅ. We find a tentative correlation between detected C IV absorption strength and star formation, paralleling the strong correlation seen in highly ionized oxygen for L ∼ L* galaxies by the COS-Halos survey. The data imply a large carbon reservoir in the circumgalactic medium (CGM) of these galaxies, corresponding to a minimum carbon mass of ≳ 1.2 × 10{sup 6} M {sub ☉} out to ∼110 kpc. This mass is comparable to the carbon mass in the interstellar medium and exceeds the carbon mass currently in the stars of these galaxies. The C IV absorption seen around these sub-L* galaxies can account for almost two-thirds of all W{sub r} ≥ 100 mÅ C IV absorption detected at low z. Comparing the C IV covering fraction with hydrodynamical simulations, we find that an energy-driven wind model is consistent with the observations whereas a wind model of constant velocity fails to reproduce the CGM or the galaxy properties.

  7. Massive star-forming host galaxies of quasars on Sloan digital sky survey stripe 82

    SciTech Connect

    Matsuoka, Yoshiki; Strauss, Michael A.; Price, Ted N. III; DiDonato, Matthew S.

    2014-01-10

    The stellar properties of about 800 galaxies hosting optically luminous, unobscured quasars at z < 0.6 are analyzed. Deep co-added Sloan Digital Sky Survey (SDSS) images of the quasars on Stripe 82 are decomposed into nucleus and host galaxy using point spread function and Sérsic models. The systematic errors in the measured galaxy absolute magnitudes and colors are estimated to be less than 0.5 mag and 0.1 mag, respectively, with simulated quasar images. The effect of quasar light scattered by the interstellar medium is also carefully addressed. The measured quasar-to-galaxy ratio in total flux decreases toward longer wavelengths, from ∼8 in the u band to ∼1 in the i and z bands. We find that the SDSS quasars are hosted exclusively by massive galaxies (stellar mass M {sub star} > 10{sup 10} M {sub ☉}), which is consistent with previous results for less luminous narrow-line (obscured) active galactic nuclei (AGNs). The quasar hosts are very blue and almost absent on the red sequence, showing stark contrast to the color-magnitude distribution of normal galaxies. The fact that more powerful AGNs reside in galaxies with higher star-formation efficiency may indicate that negative AGN feedback, if it exists, is not concurrent with the most luminous phase of AGNs. We also find positive correlation between the mass of supermassive black holes (SMBHs; M {sub BH}) and host stellar mass, but the M {sub BH}-M {sub star} relation is offset toward large M {sub BH} or small M {sub star} compared to the local relation. While this could indicate that SMBHs grow earlier than do their host galaxies, such an argument is not conclusive, as the effect may be dominated by observational biases.

  8. The Effect of Host Galaxies on Type Ia Supernovae in the SDSS-II Supernova Survey

    SciTech Connect

    Lampeitl, Hubert; Smith, Mathew; Nichol, Robert C.; Bassett, Bruce; Cinabro, David; Dilday, Benjamin; Foley, Ryan J.; Frieman, Joshua A.; Garnavich, Peter M.; Goobar, Ariel; Im, Myungshin; /Seoul Natl. U. /Rutgers U., Piscataway

    2010-05-01

    We present an analysis of the host galaxy dependencies of Type Ia Supernovae (SNe Ia) from the full three year sample of the SDSS-II Supernova Survey. We re-discover, to high significance, the strong correlation between host galaxy type and the width of the observed SN light curve, i.e., fainter, quickly declining SNe Ia favor passive host galaxies, while brighter, slowly declining Ia's favor star-forming galaxies. We also find evidence (at between 2 to 3{sigma}) that SNe Ia are {approx_equal} 0.1 magnitudes brighter in passive host galaxies, than in star-forming hosts, after the SN Ia light curves have been standardized using the light curve shape and color variations: This difference in brightness is present in both the SALT2 and MCLS2k2 light curve fitting methodologies. We see evidence for differences in the SN Ia color relationship between passive and star-forming host galaxies, e.g., for the MLCS2k2 technique, we see that SNe Ia in passive hosts favor a dust law of R{sub V} {approx_equal} 1, while SNe Ia in star-forming hosts require R{sub V} {approx} 2. The significance of these trends depends on the range of SN colors considered. We demonstrate that these effects can be parameterized using the stellar mass of the host galaxy (with a confidence of > 4{sigma}) and including this extra parameter provides a better statistical fit to our data. Our results suggest that future cosmological analyses of SN Ia samples should include host galaxy information.

  9. Deep X-ray and UV Surveys of Galaxies with Chandra, XMM-Newton, and GALEX

    NASA Technical Reports Server (NTRS)

    Hornschemeier, Ann

    2006-01-01

    Only with the deepest Chandra surveys has X-ray emission from normal and star forming galaxies (as opposed to AGN, which dominate the X-ray sky) been accessible at cosmologically interesting distances. The X-ray emission from accreting binaries provide a critical glimpse into the binary phase of stellar evolution and studies of the hot gas reservoir constrain past star formation. UV studies provide important, sensitive diagnostics of the young star forming populations and provide the most mature means for studying galaxies at 2 < zeta < 4. This talk will review current progress on studying X-ray emission in concert with UV emission from normal/star-forming galaxies at higher redshift. We will also report on our new, deep surveys with GALEX and XMM-Newton in the nearby Coma cluster. These studies are relevant to DEEP06 as Coma is the nearest rich cluster of galaxies and provides an important benchmark for high-redshift studies in the X-ray and UV wavebands. The 30 ks GALEX (note: similar depth to the GALEX Deep Imaging Survey) and the 110 ks XMM observations provide extremely deep coverage of a Coma outskirts field, allowing the construction of the UV and X-ray luminosity function of galaxies and important constraints on star formation scaling relations such as the X-ray-Star Formation Rate correlation and the X-ray/Stellar Mass correlation. We will discuss what we learn from these deep observations of Coma, including the recently established suppression of the X-ray emission from galaxies in the Coma outskirts that is likely associated with lower levels of past star formation and/or the results of tidal gas stripping.

  10. The XMM Cluster Survey: The Halo Occupation Number of BOSS galaxies in X-ray clusters

    NASA Astrophysics Data System (ADS)

    Mehrtens, Nicola; Romer, A. Kathy; Nichol, Robert C.; Collins, Chris A.; Sahlén, Martin; Rooney, Philip J.; Mayers, Julian A.; Bermeo-Hernandez, A.; Bristow, Martyn; Capozzi, Diego; Christodoulou, L.; Comparat, Johan; Hilton, Matt; Hoyle, Ben; Kay, Scott T.; Liddle, Andrew R.; Mann, Robert G.; Masters, Karen; Miller, Christopher J.; Parejko, John K.; Prada, Francisco; Ross, Ashley J.; Schneider, Donald P.; Stott, John P.; Streblyanska, Alina; Viana, Pedro T. P.; White, Martin; Wilcox, Harry; Zehavi, Idit

    2016-08-01

    We present a direct measurement of the mean halo occupation distribution (HOD) of galaxies taken from the eleventh data release (DR11) of the Sloan Digital Sky Survey-III Baryon Acoustic Oscillation Survey (BOSS). The HOD of BOSS low-redshift (LOWZ: 0.2 < z < 0.4) and Constant-Mass (CMASS: 0.43 < z < 0.7) galaxies is inferred via their association with the dark-matter halos of 174 X-ray-selected galaxy clusters drawn from the XMM Cluster Survey (XCS). Halo masses are determined for each galaxy cluster based on X-ray temperature measurements, and range between log10(M180/M⊙) = 13 - 15. Our directly-measured HODs are consistent with the HOD-model fits inferred via the galaxy-clustering analyses of Parejko et al. (2013) for the BOSS LOWZ sample and White et al. (2011) for the BOSS CMASS sample. Under the simplifying assumption that the other parameters that describe the HOD hold the values measured by these authors, we have determined a best-fit alpha-index of 0.91±0.08 and 1.27^{+0.03}_{-0.04} for the CMASS and LOWZ HOD, respectively. These alpha-index values are consistent with those measured by White et al. (2011) and Parejko et al. (2013). In summary, our study provides independent support for the HOD-models assumed during the development of the BOSS mock-galaxy catalogues that have subsequently been used to derive BOSS cosmological constraints.

  11. Star formation and galaxy evolution since z˜2: Results from multiwavelength surveys

    NASA Astrophysics Data System (ADS)

    Brisbin, Drew

    Our recent studies in galaxy evolution have revealed a surprising new paradigm of star formation. Contrary to the notion that major mergers play an increasingly dominant role going backwards in cosmic history, we find that over the last ˜10 Gyr, much of star formation has been fueled by accreting cold gas from the cosmic web. Accretion rates were presumably larger in the past, so star forming systems may have very different properties in the early Universe and today. Large scale astronomical surveys, such as the Herschel Multi-Tiered Extragalactic Survey (HerMES), and the Sloan Digital Sky Survey (SDSS) have provided a wealth of extragalactic data covering a statistically large number of sources. Targeted, niche surveys, like our fine structure line survey of star forming galaxies in the early Universe observed with the redshift (z) Early Universe Spectrometer (ZEUS) have provided detailed observations of high interest sources. We have made use of this diverse set of data to study galaxy evolution from the epoch of peak star formation at z=1-2 up to the present. Data from HerMES is a reliable probe of infrared emission, particularly useful for characterizing the far infrared dust peak, and therefore determining star formation rates out to redshifts of a few. Deep integrations with the Herschel SPIRE photometer rapidly reach the confusion limit, tempering its utility in studying faint high redshift galaxies. With appropriate care taken to identify blended sources, however, HerMES data is useful in identifying bright, redshifted, star forming sources. We have compiled spectral energy distributions from HerMES and ancillary data and found that, even sources at high redshift are well fit by local star forming galaxy templates. In the local Universe, spectroscopic SDSS data has allowed us to estimate crucial galaxy properties on ˜105 sources, providing an opportunity to observe general statistical trends, and constrain theories of galaxy evolution. A toy model of cold

  12. Searching for Galaxy Clusters in the VST-KiDS Survey

    NASA Astrophysics Data System (ADS)

    Radovich, M.; Puddu, E.; Bellagamba, F.; Moscardini, L.; Roncarelli, M.; Getman, F.; Grado, A.

    We present the methods and first results of the search for galaxy clusters in the Kilo Degree Survey (KiDS). The adopted algorithm and the criterium for selecting the member galaxies are illustrated. Here we report the preliminary results obtained over a small area (7 deg2), and the comparison of our cluster candidates with those found in the RedMapper and SZ Planck catalogues; the analysis to a larger area (148 deg2) is currently in progress. By the KiDS cluster search, we expect to increase the completeness of the clusters catalogue to z = 0.6-0.7 compared to RedMapper.

  13. The SAMI Galaxy Survey: cubism and covariance, putting round pegs into square holes

    NASA Astrophysics Data System (ADS)

    Sharp, R.; Allen, J. T.; Fogarty, L. M. R.; Croom, S. M.; Cortese, L.; Green, A. W.; Nielsen, J.; Richards, S. N.; Scott, N.; Taylor, E. N.; Barnes, L. A.; Bauer, A. E.; Birchall, M.; Bland-Hawthorn, J.; Bloom, J. V.; Brough, S.; Bryant, J. J.; Cecil, G. N.; Colless, M.; Couch, W. J.; Drinkwater, M. J.; Driver, S.; Foster, C.; Goodwin, M.; Gunawardhana, M. L. P.; Ho, I.-T.; Hampton, E. J.; Hopkins, A. M.; Jones, H.; Konstantopoulos, I. S.; Lawrence, J. S.; Leslie, S. K.; Lewis, G. F.; Liske, J.; López-Sánchez, Á. R.; Lorente, N. P. F.; McElroy, R.; Medling, A. M.; Mahajan, S.; Mould, J.; Parker, Q.; Pracy, M. B.; Obreschkow, D.; Owers, M. S.; Schaefer, A. L.; Sweet, S. M.; Thomas, A. D.; Tonini, C.; Walcher, C. J.

    2015-01-01

    We present a methodology for the regularization and combination of sparse sampled and irregularly gridded observations from fibre-optic multiobject integral field spectroscopy. The approach minimizes interpolation and retains image resolution on combining subpixel dithered data. We discuss the methodology in the context of the Sydney-AAO multiobject integral field spectrograph (SAMI) Galaxy Survey underway at the Anglo-Australian Telescope. The SAMI instrument uses 13 fibre bundles to perform high-multiplex integral field spectroscopy across a 1° diameter field of view. The SAMI Galaxy Survey is targeting ˜3000 galaxies drawn from the full range of galaxy environments. We demonstrate the subcritical sampling of the seeing and incomplete fill factor for the integral field bundles results in only a 10 per cent degradation in the final image resolution recovered. We also implement a new methodology for tracking covariance between elements of the resulting data cubes which retains 90 per cent of the covariance information while incurring only a modest increase in the survey data volume.

  14. Measuring galaxy environment with the synergy of future photometric and spectroscopic surveys

    NASA Astrophysics Data System (ADS)

    Cucciati, O.; Marulli, F.; Cimatti, A.; Merson, A. I.; Norberg, P.; Pozzetti, L.; Baugh, C. M.; Branchini, E.

    2016-10-01

    We exploit the synergy between low-resolution spectroscopy and photometric redshifts to study environmental effects on galaxy evolution in slitless spectroscopic surveys from space. As a test case, we consider the future Euclid Deep survey (˜40 deg2), which combines a slitless spectroscopic survey limited at Hα flux ≥5 × 10-17 erg cm-2 s-1 and a photometric survey limited in H band (H ≤ 26). We use Euclid-like galaxy mock catalogues, in which we anchor the photometric redshifts to the 3D galaxy distribution of the available spectroscopic redshifts. We then estimate the local density contrast by counting objects in cylindrical cells with radius from 1 to 10 h-1Mpc, over the redshift range 0.9 < z < 1.8. We compare this density field with the one computed in a mock catalogue with the same depth as the Euclid Deep survey (H = 26) but without redshift measurement errors. We find that our method successfully separates high- from low-density environments (the last from the first quintile of the density distribution), with higher efficiency at low redshift and large cells: the fraction of low-density regions mistaken by high-density peaks is <1 per cent for all scales and redshifts explored, but for scales of 1 h-1Mpc for which is a few per cent. These results show that we can efficiently study environment in photometric samples if spectroscopic information is available for a smaller sample of objects that sparsely samples the same volume. We demonstrate that these studies are possible in the Euclid Deep survey, i.e. in a redshift range in which environmental effects are different from those observed in the local Universe, hence providing new constraints for galaxy evolution models.

  15. A 7 deg2 survey for galaxy-scale gravitational lenses with the HST imaging archive

    NASA Astrophysics Data System (ADS)

    Pawase, R. S.; Courbin, F.; Faure, C.; Kokotanekova, R.; Meylan, G.

    2014-04-01

    We present the results of a visual search for galaxy-scale gravitational lenses in ˜7 deg2 of Hubble Space Telescope (HST) images. The data set comprises the whole imaging data ever taken with the Advanced Camera for Surveys (ACS) in the filter F814W (I-band) up to 2011 August 31, i.e. 6.03 deg2 excluding the field of the Cosmic Evolution Survey which has been the subject of a separate visual search. In addition, we have searched for lenses in the whole Wide Field Camera 3 (WFC3) near-IR imaging data set in all filters (1.01 deg2) up to the same date. Our primary goal is to provide a sample of lenses with a broad range of different morphologies and lens-source brightness contrast in order to estimate a lower limit to the number of galaxy-scale strong lenses in the future Euclid survey in its VIS band. Our criteria to select lenses are purely morphological as we do not use any colour or redshift information. The final candidate selection is very conservative hence leading to a nearly pure but incomplete sample. We find 49 new lens candidates: 40 in the ACS images and 9 in the WFC3 images. Out of these, 16 candidates are secure lenses owing to their striking morphology, 21 more are very good candidates and 12 more have morphologies compatible with gravitational lensing but also compatible with other astrophysical objects such as ring and chain galaxies or mergers. Interestingly, some lens galaxies include low surface brightness galaxies, compact groups and mergers. The imaging data set is heterogeneous in depth and spans a broad range of galactic latitudes. It is therefore insensitive to cosmic variance and allows us to estimate the number of galaxy-scale strong lenses on the sky for a putative survey depth, which is the main result of this work. Because of the incompleteness of the sample, the estimated lensing rates should be taken as lower limits. Using these, we anticipate that a 15 000 deg2 space survey such as Euclid will find at least 60 000 galaxy

  16. THE ADVANCED CAMERA FOR SURVEYS NEARBY GALAXY SURVEY TREASURY. V. RADIAL STAR FORMATION HISTORY OF NGC 300

    SciTech Connect

    Gogarten, Stephanie M.; Dalcanton, Julianne J.; Williams, Benjamin F.; Roskar, Rok; Gilbert, Karoline M.; Quinn, Thomas R.; Holtzman, Jon; Seth, Anil C.; Dolphin, Andrew; Weisz, Daniel; Skillman, Evan; Cole, Andrew; Debattista, Victor P.; Olsen, Knut; De Jong, Roelof S.; Karachentsev, Igor D.

    2010-04-01

    We present new Hubble Space Telescope (HST) observations of NGC 300 taken as part of the Advanced Camera for Surveys Nearby Galaxy Survey Treasury (ANGST). Individual stars are resolved in these images down to an absolute magnitude of M{sub F814W} = 1.0 (below the red clump). We determine the star formation history of the galaxy in six radial bins by comparing our observed color-magnitude diagrams (CMDs) with synthetic CMDs based on theoretical isochrones. We find that the stellar disk out to 5.4 kpc is primarily old, in contrast with the outwardly similar galaxy M33. We determine the scale length as a function of age and find evidence for inside-out growth of the stellar disk: the scale length has increased from 1.1 +- 0.1 kpc 10 Gyr ago to 1.3 +- 0.1 kpc at present, indicating a buildup in the fraction of young stars at larger radii. As the scale length of M33 has recently been shown to have increased much more dramatically with time, our results demonstrate that two galaxies with similar sizes and morphologies can have very different histories. With an N-body simulation of a galaxy designed to be similar to NGC 300, we determine that the effects of radial migration should be minimal. We trace the metallicity gradient as a function of time and find a present-day metallicity gradient consistent with that seen in previous studies. Consistent results are obtained from archival images covering the same radial extent but differing in placement and filter combination.

  17. Emission line galaxy pairs up to z=1.5 from the WISP survey

    NASA Astrophysics Data System (ADS)

    Teplitz, Harry I.; Dai, Yu Sophia; Malkan, Matthew Arnold; Scarlata, Claudia; Colbert, James W.; Atek, Hakim; Bagley, Micaela B.; Baronchelli, Ivano; Bedregal, Alejandro; Beck, Melanie; Bunker, Andrew; Dominguez, Alberto; Hathi, Nimish P.; Henry, Alaina L.; Mehta, Vihang; Pahl, Anthony; Rafelski, Marc; Ross, Nathaniel; Rutkowski, Michael J.; Siana, Brian D.; WISPs Team

    2016-01-01

    We present a sample of spectroscopically identified emission line galaxy pairs up to z=1.5 from WISPs (WFC3 Infrared Spectroscopic Parallel survey) using high resolution direct and grism images from HST. We searched ~150 fields with a covered area of ~600 arcmin^2, and a comoving volume of > 400 Gpc^3 at z=1-2, and found ~80 very close physical pairs (projected separation Dp < 50 h^{-1}kpc, relative velocity d_v < 500 kms^{-1}), and ~100 close physical pairs (50 < Dp < 100 h^{-1}kpc, d_v < 1000 kms^{-1}) of emission line galaxies, including two dozen triplets and quadruples. In this poster we present the multi-wavelength data, star formation rate (SFR), mass ratio, and study the merger rate evolution with this special galaxy pair sample.

  18. The VIRUS-P Exploration of Nearby Galaxies (VENGA): Survey Design and First Results

    NASA Astrophysics Data System (ADS)

    Blanc, G. A.; Gebhardt, K.; Heiderman, A.; Evans, N. J., II; Jogee, S.; van den Bosch, R.; Marinova, I.; Weinzirl, T.; Yoachim, P.; Drory, N.; Fabricius, M.; Fisher, D.; Hao, L.; MacQueen, P. J.; Shen, J.; Hill, G. J.; Kormendy, J.

    2010-10-01

    VENGA is a large-scale extragalactic IFU survey, which maps the bulges, bars and large parts of the outer disks of 32 nearby normal spiral galaxies. The targets are chosen to span a wide range in Hubble types, star formation activities, morphologies, and inclinations, at the same time of having vast available multi-wavelength coverage from the far-UV to the mid-IR, and available CO and 21cm mapping. The VENGA dataset will provide 2D maps of the SFR, stellar and gas kinematics, chemical abundances, ISM density and ionization states, dust extinction and stellar populations for these 32 galaxies. The uniqueness of the VIRUS-P large field of view permits these large-scale mappings to be performed. VENGA will allow us to correlate all these important quantities throughout the different environments present in galactic disks, allowing the conduction of a large number of studies in star formation, structure assembly, galactic feedback and ISM in galaxies.

  19. Surveying for Dwarf Galaxies Within Voids FN2 and FN8

    NASA Astrophysics Data System (ADS)

    McNeil, Stephen; Draper, Chris; Moody, J. Ward

    2016-10-01

    The presence or absence of dwarf galaxies with Mr' > -14 in low-density volumes correlates with dark matter halos and how they affect galaxy formation. We are conducting a redshifted Hα imaging survey for dwarf galaxies with Mr' > -13 in the heart of the well-defined voids FN2 and FN8 using the KPNO 4m Mayall telescope and Mosaic Imager. These data have furnished over 600 strong candidates in a four square degree area. Follow-up spectra finding none of these candidates to be within the void volumes will constrain the dwarf population there to be 2 to 8% of the cosmic mean. Conversely, finding even one Hα dwarf in the void heart will challenge several otherwise successful theories of large-scale structure formation.

  20. THE CLUSTERING OF GALAXIES IN THE SDSS-III BARYON OSCILLATION SPECTROSCOPIC SURVEY: LUMINOSITY AND COLOR DEPENDENCE AND REDSHIFT EVOLUTION

    SciTech Connect

    Guo Hong; Zehavi, Idit; Zheng Zheng; Weinberg, David H.; Berlind, Andreas A.; Blanton, Michael; Chen Yanmei; Eisenstein, Daniel J.; McBride, Cameron K.; Ho, Shirley; Ross, Nicholas P.; Kazin, Eyal; Manera, Marc; Maraston, Claudia; Percival, Will J.; Ross, Ashley J.; Samushia, Lado; Nuza, Sebastian E.; Padmanabhan, Nikhil; Parejko, John K.; and others

    2013-04-20

    We measure the luminosity and color dependence and the redshift evolution of galaxy clustering in the Sloan Digital Sky Survey-III Baryon Oscillation Spectroscopic Survey Ninth Data Release. We focus on the projected two-point correlation function (2PCF) of subsets of its CMASS sample, which includes about 260,000 galaxies over {approx}3300 deg{sup 2} in the redshift range 0.43 < z < 0.7. To minimize the selection effect on galaxy clustering, we construct well-defined luminosity and color subsamples by carefully accounting for the CMASS galaxy selection cuts. The 2PCF of the whole CMASS sample, if approximated by a power-law, has a correlation length of r{sub 0} = 7.93 {+-} 0.06 h {sup -1} Mpc and an index of {gamma} = 1.85 {+-} 0.01. Clear dependences on galaxy luminosity and color are found for the projected 2PCF in all redshift bins, with more luminous and redder galaxies generally exhibiting stronger clustering and steeper 2PCF. The color dependence is also clearly seen for galaxies within the red sequence, consistent with the behavior of SDSS-II main sample galaxies at lower redshifts. At a given luminosity (k + e corrected), no significant evolution of the projected 2PCFs with redshift is detected for red sequence galaxies. We also construct galaxy samples of fixed number density at different redshifts, using redshift-dependent magnitude thresholds. The clustering of these galaxies in the CMASS redshift range is found to be consistent with that predicted by passive evolution. Our measurements of the luminosity and color dependence and redshift evolution of galaxy clustering will allow for detailed modeling of the relation between galaxies and dark matter halos and new constraints on galaxy formation and evolution.

  1. DUAL SUPERMASSIVE BLACK HOLE CANDIDATES IN THE AGN AND GALAXY EVOLUTION SURVEY

    SciTech Connect

    Comerford, Julia M.; Schluns, Kyle; Greene, Jenny E.; Cool, Richard J.

    2013-11-01

    Dual supermassive black holes (SMBHs) with kiloparsec-scale separations in merger-remnant galaxies are informative tracers of galaxy evolution, but the avenue for identifying them in large numbers for such studies is not yet clear. One promising approach is to target spectroscopic signatures of systems where both SMBHs are fueled as dual active galactic nuclei (AGNs), or where one SMBH is fueled as an offset AGN. Dual AGNs may produce double-peaked narrow AGN emission lines, while offset AGNs may produce single-peaked narrow AGN emission lines with line-of-sight velocity offsets relative to the host galaxy. We search for such dual and offset systems among 173 Type 2 AGNs at z < 0.37 in the AGN and Galaxy Evolution Survey (AGES), and we find two double-peaked AGNs and five offset AGN candidates. When we compare these results to a similar search of the DEEP2 Galaxy Redshift Survey and match the two samples in color, absolute magnitude, and minimum velocity offset, we find that the fraction of AGNs that are dual SMBH candidates increases from z = 0.25 to z = 0.7 by a factor of ∼6 (from 2/70 to 16/91, or 2.9{sup +3.6}{sub -1.9}% to 18{sup +5}{sub -5}%). This may be associated with the rise in the galaxy merger fraction over the same cosmic time. As further evidence for a link with galaxy mergers, the AGES offset and dual AGN candidates are tentatively ∼3 times more likely than the overall AGN population to reside in a host galaxy that has a companion galaxy (from 16/173 to 2/7, or 9{sup +3}{sub -2}% to 29{sub -19}{sup +26}%). Follow-up observations of the seven offset and dual AGN candidates in AGES will definitively distinguish velocity offsets produced by dual SMBHs from those produced by narrow-line region kinematics, and will help sharpen our observational approach to detecting dual SMBHs.

  2. Morphological parameters of a Spitzer survey of stellar structure in galaxies

    SciTech Connect

    Holwerda, B. W.; Muñoz-Mateos, J.-C.; Sheth, K.; Kim, T.; Meidt, S.; Mizusawa, T.; Hinz, J. L.; Zaritsky, D.; Regan, M. W.; Gil de Paz, A.; Menéndez-Delmestre, K.; Seibert, M.; Ho, L. C.; Gadotti, D. A.; Erroz-Ferrer, S. E-mail: benne.holwerda@gmail.com [Instituto de Astrofísica de Canarias, Vía Láctea s and others

    2014-01-20

    The morphology of galaxies can be quantified to some degree using a set of scale-invariant parameters. Concentration (C), asymmetry (A), smoothness (S), the Gini index (G), the relative contribution of the brightest pixels to the second-order moment of the flux (M {sub 20}), ellipticity (E), and the Gini index of the second-order moment (G{sub M} ) have all been applied to morphologically classify galaxies at various wavelengths. Here, we present a catalog of these parameters for the Spitzer Survey of stellar structure in Galaxies, a volume-limited, near-infrared (NIR) imaging survey of nearby galaxies using the 3.6 and 4.5 μm channels of the Infrared Array Camera on board the Spitzer Space Telescope. Our goal is to provide a reference catalog of NIR quantified morphology for high-redshift studies and galaxy evolution models with enough detail to resolve stellar mass morphology. We explore where normal, non-interacting galaxies—those typically found on the Hubble tuning fork—lie in this parameter space and show that there is a tight relation between concentration (C {sub 82}) and M {sub 20} for normal galaxies. M {sub 20} can be used to classify galaxies into earlier and later types (i.e., to separate spirals from irregulars). Several criteria using these parameters exist to select systems with a disturbed morphology, i.e., those that appear to be undergoing a tidal interaction. We examine the applicability of these criteria to Spitzer NIR imaging. We find that four relations, based on the parameters A and S, G and M {sub 20}, G{sub M} , C, and M {sub 20}, respectively, select outliers in morphological parameter space, but each selects different subsets of galaxies. Two criteria (G{sub M} > 0.6, G > –0.115 × M {sub 20} + 0.384) seem most appropriate to identify possible mergers and the merger fraction in NIR surveys. We find no strong relation between lopsidedness and most of these morphological parameters, except for a weak dependence of lopsidedness on

  3. The 400 Square Degree ROSAT PSPC Galaxy Cluster Survey: Catalog and Statistical Calibration

    NASA Astrophysics Data System (ADS)

    Burenin, R. A.; Vikhlinin, A.; Hornstrup, A.; Ebeling, H.; Quintana, H.; Mescheryakov, A.

    2007-10-01

    We present a catalog of galaxy clusters detected in a new ROSAT PSPC survey. The survey is optimized to sample, at high redshifts, the mass range corresponding to T>5 keV clusters at z=0. Technically, our survey is the extension of the 160 square degree survey (160d). We use the same detection algorithm, thus preserving high quality of the resulting sample; the main difference is a significant increase in sky coverage. The new survey covers 397 deg2 and is based on 1610 high Galactic latitude ROSAT PSPC pointings, virtually all pointed ROSAT data suitable for the detection of distant clusters. The search volume for X-ray luminous clusters within z<1 exceeds that of the entire local universe (z<0.1). We detected 287 extended X-ray sources with fluxes f>1.4×10-13 ergs s-1 cm-2 in the 0.5-2 keV energy band, of which 266 (93%) are optically confirmed as galaxy clusters, groups or individual elliptical galaxies. This paper provides a description of the input data, the statistical calibration of the survey via Monte Carlo simulations, and the catalog of detected clusters. We also compare the basic results to those from previous, smaller area surveys and find good agreement for the logN-logS distribution and the local X-ray luminosity function. Our sample clearly shows a decrease in the number density for the most luminous clusters at z>0.3. The comparison of our ROSAT-derived fluxes with the accurate Chandra measurements for a subset of high-redshift clusters demonstrates the validity of the 400 square degree survey's statistical calibration.

  4. EARLY-TYPE GALAXIES IN THE PEARS SURVEY: PROBING THE STELLAR POPULATIONS AT MODERATE REDSHIFT

    SciTech Connect

    Ferreras, Ignacio; Pasquali, Anna; Malhotra, Sangeeta; Rhoads, James; Cohen, Seth; Windhorst, Rogier; Pirzkal, Nor; Grogin, Norman; Koekemoer, Anton M.; Panagia, Nino; Lisker, Thorsten; Daddi, Emanuele; Hathi, Nimish P.

    2009-11-20

    Using Hubble Space Telescope (HST)/Advanced Camera for Surveys (ACS) slitless grism spectra from the PEARS program, we study the stellar populations of morphologically selected early-type galaxies in the GOODS North and South fields. The sample-extracted from a visual classification of the (v2.0) HST/ACS images and restricted to redshifts z > 0.4-comprises 228 galaxies (i {sub F775W} < 24 mag, AB) out to z approx< 1.3 over 320 arcmin{sup 2}, with a median redshift z {sub M} = 0.75. This work significantly increases our previous sample from the GRAPES survey in the HUDF (18 galaxies over approx11 arcmin{sup 2}). The grism data allow us to separate the sample into 'red' and 'blue' spectra, with the latter comprising 15% of the total. Three different grids of models parameterizing the star formation history are used to fit the low-resolution spectra. Over the redshift range of the sample-corresponding to a cosmic age between 5 and 10 Gyr-we find a strong correlation between stellar mass and average age, whereas the spread of ages (defined by the root mean square of the distribution) is roughly approx1 Gyr and independent of stellar mass. The best-fit parameters suggest that it is the formation epoch and not the formation timescale that best correlates with mass in early-type galaxies. This result-along with the recently observed lack of evolution of the number density of massive galaxies-motivates the need for a channel of (massive) galaxy formation bypassing any phase in the blue cloud, as suggested by the simulations of Dekel et al.

  5. Percolation galaxy groups and clusters in the sdss redshift survey: identification, catalogs, and the multiplicity function

    SciTech Connect

    Berlind, Andreas A.; Frieman, Joshua A.; Weinberg, David H.; Blanton, Michael R.; Warren, Michael S.; Abazajian, Kevork; Scranton, Ryan; Hogg, David W.; Scoccimarro, Roman; Bahcall, Neta A.; Brinkmann, J.; Gott, J.Richard, III; Kleinman, S.J.; Krzesinski, J.; Lee, Brian C.; Miller, Christopher J.; Nitta, Atsuko; Schneider, Donald P.; Tucker, Douglas L.; Zehavi, Idit; /CCPP, New York /Chicago U., Astron. Astrophys. Ctr. /Ohio State U., Dept. Astron. /Los Alamos /Pittsburgh U. /Princeton U. /Subaru Telescope /Apache Point Observ. /Mt. Suhora Observ., Cracow /LBL, Berkeley /Cerro-Tololo InterAmerican Obs. /Penn State U., Astron. Astrophys. /Fermilab /Arizona U., Astron. Dept. - Steward Observ. /Case Western Reserve U.

    2006-01-01

    We identify galaxy groups and clusters in volume-limited samples of the SDSS redshift survey, using a redshift-space friends-of-friends algorithm. We optimize the friends-of-friends linking lengths to recover galaxy systems that occupy the same dark matter halos, using a set of mock catalogs created by populating halos of N-body simulations with galaxies. Extensive tests with these mock catalogs show that no combination of perpendicular and line-of-sight linking lengths is able to yield groups and clusters that simultaneously recover the true halo multiplicity function, projected size distribution, and velocity dispersion. We adopt a linking length combination that yields, for galaxy groups with ten or more members: a group multiplicity function that is unbiased with respect to the true halo multiplicity function; an unbiased median relation between the multiplicities of groups and their associated halos; a spurious group fraction of less than {approx}1%; a halo completeness of more than {approx}97%; the correct projected size distribution as a function of multiplicity; and a velocity dispersion distribution that is {approx}20% too low at all multiplicities. These results hold over a range of mock catalogs that use different input recipes of populating halos with galaxies. We apply our group-finding algorithm to the SDSS data and obtain three group and cluster catalogs for three volume-limited samples that cover 3495.1 square degrees on the sky. We correct for incompleteness caused by fiber collisions and survey edges, and obtain measurements of the group multiplicity function, with errors calculated from realistic mock catalogs. These multiplicity function measurements provide a key constraint on the relation between galaxy populations and dark matter halos.

  6. THE DISTRIBUTION OF FAINT SATELLITES AROUND CENTRAL GALAXIES IN THE CANADA-FRANCE-HAWAII TELESCOPE LEGACY SURVEY

    SciTech Connect

    Jiang, C. Y.; Jing, Y. P.; Li, Cheng

    2012-11-20

    We investigate the radial number density profile and the abundance distribution of faint satellites around central galaxies in the low-redshift universe using the Canada-France-Hawaii Telescope (CFHT) Legacy Survey. We consider three samples of central galaxies with magnitudes of M {sub r} = -21, -22, and -23 selected from the Sloan Digital Sky Survey group catalog of Yang et al. The satellite distribution around these central galaxies is obtained by cross-correlating these galaxies with the photometric catalog of the CFHT Legacy Survey. The projected radial number density of the satellites obeys a power-law form with the best-fit logarithmic slope of -1.05, independent of both the central galaxy luminosity and the satellite luminosity. The projected cross-correlation function between central and satellite galaxies exhibits a non-monotonic trend with satellite luminosity. It is most pronounced for central galaxies with M {sub r} = -21, where the decreasing trend of clustering amplitude with satellite luminosity is reversed when satellites are fainter than central galaxies by more than 2 mag. A comparison with the satellite luminosity functions in the Milky Way (MW) and M31 shows that the MW/M31 system has about twice as many satellites as around a typical central galaxy of similar luminosity. The implications for theoretical models are briefly discussed.

  7. Unusual broad-line Mg II emitters among luminous galaxies in the baryon oscillation spectroscopic survey

    SciTech Connect

    Roig, Benjamin; Blanton, Michael R.; Ross, Nicholas P.

    2014-02-01

    Many classes of active galactic nuclei (AGNs) have been observed and recorded since the discovery of Seyfert galaxies. In this paper, we examine the sample of luminous galaxies in the Baryon Oscillation Spectroscopic Survey. We find a potentially new observational class of AGNs, one with strong and broad Mg II λ2799 line emission, but very weak emission in other normal indicators of AGN activity, such as the broad-line Hα, Hβ, and the near-ultraviolet AGN continuum, leading to an extreme ratio of broad Hα/Mg II flux relative to normal quasars. Meanwhile, these objects' narrow-line flux ratios reveal AGN narrow-line regions with levels of activity consistent with the Mg II fluxes and in agreement with that of normal quasars. These AGN may represent an extreme case of the Baldwin effect, with very low continuum and high equivalent width relative to typical quasars, but their ratio of broad Mg II to broad Balmer emission remains very unusual. They may also be representative of a class of AGN where the central engine is observed indirectly with scattered light. These galaxies represent a small fraction of the total population of luminous galaxies (≅ 0.1%), but are more likely (about 3.5 times) to have AGN-like nuclear line emission properties than other luminous galaxies. Because Mg II is usually inaccessible for the population of nearby galaxies, there may exist a related population of broad-line Mg II emitters in the local universe which is currently classified as narrow-line emitters (Seyfert 2 galaxies) or low ionization nuclear emission-line regions.

  8. Radial gas motions in The H I Nearby Galaxy Survey (THINGS)

    NASA Astrophysics Data System (ADS)

    Schmidt, Tobias M.; Bigiel, Frank; Klessen, Ralf S.; de Blok, W. J. G.

    2016-04-01

    The study of 21 cm line observations of atomic hydrogen allows detailed insight into the kinematics of spiral galaxies. We use sensitive high-resolution Very Large Array data from The H I Nearby Galaxy Survey (THINGS) to search for radial gas flows primarily in the outer parts (up to 3 × r25) of 10 nearby spiral galaxies. Inflows are expected to replenish the gas reservoir and fuel star formation under the assumption that galaxies evolve approximately in steady state. We carry out a detailed investigation of existing tilted ring fitting schemes and discover systematics that can hamper their ability to detect signatures of radial flows. We develop a new Fourier decomposition scheme that fits for rotational and radial velocities and simultaneously determines position angle and inclination as a function of radius. Using synthetic velocity fields we show that our novel fitting scheme is less prone to such systematic errors and that it is well suited to detect radial inflows in discs. We apply our fitting scheme to 10 THINGS galaxies and find clear indications of, at least partly previously unidentified, radial gas flows, in particular for NGC 2403 and NGC 3198 and to a lesser degree for NGC 7331, NGC 2903 and NGC 6946. The mass flow rates are of the same order but usually larger than the star formation rates. At least for these galaxies a scenario in which continuous mass accretion feeds star formation seems plausible. The other galaxies show a more complicated picture with either no clear inflow, outward motions or complex kinematic signatures.

  9. DISCOVERY OF LYMAN BREAK GALAXIES AT z {approx} 7 FROM THE zFourGE SURVEY

    SciTech Connect

    Tilvi, V.; Papovich, C.; Tran, K.-V. H.; Labbe, I.; Straatman, C. M. S.; Spitler, L. R.; Glazebrook, K.; Kacprzak, G. G.; Persson, S. E.; Monson, A.; Quadri, R. F.; Kelson, D. D.; Van Dokkum, P.; Ashby, M. L. N.; Fazio, G. G.; Faber, S. M.; Ferguson, H. C.; Grogin, N. A.; Koekemoer, A. M.; and others

    2013-05-01

    Star-forming galaxies at redshifts z > 6 are likely responsible for the reionization of the universe, and it is important to study the nature of these galaxies. We present three candidates for z {approx} 7 Lyman break galaxies (LBGs) from a 155 arcmin{sup 2} area in the CANDELS/COSMOS field imaged by the deep FourStar Galaxy Evolution (zFourGE) survey. The FourStar medium-band filters provide the equivalent of R {approx} 10 spectroscopy, which cleanly distinguishes between z {approx} 7 LBGs and brown dwarf stars. The distinction between stars and galaxies based on an object's angular size can become unreliable even when using Hubble Space Telescope imaging; there exists at least one very compact z {approx} 7 candidate (FWHM {approx} 0.5-1 kpc) that is indistinguishable from a point source. The medium-band filters provide narrower redshift distributions compared with broadband-derived redshifts. The UV luminosity function derived using the three z {approx} 7 candidates is consistent with previous studies, suggesting an evolution at the bright end (M{sub UV} {approx} -21.6 mag) from z {approx} 7 to z {approx} 5. Fitting the galaxies' spectral energy distributions, we predict Ly{alpha} equivalent widths for the two brightest LBGs, and find that the presence of a Ly{alpha} line affects the medium-band flux thereby changing the constraints on stellar masses and UV spectral slopes. This illustrates the limitations of deriving LBG properties using only broadband photometry. The derived specific star-formation rates for the bright LBGs are {approx}13 Gyr{sup -1}, slightly higher than the lower-luminosity LBGs, implying that the star-formation rate increases with stellar mass for these galaxies.

  10. RED-SEQUENCE GALAXIES AT HIGH REDSHIFT BY THE COMBO-17+4 SURVEY

    SciTech Connect

    Nicol, Marie-Helene; Meisenheimer, Klaus; Wolf, Christian; Tapken, Christian E-mail: meise@mpia.de E-mail: ctapken@aip.de

    2011-01-20

    We investigate the evolution of the galaxy population since redshift 2 with a focus on the color bimodality and mass density of the red sequence. We obtain precise and reliable photometric redshifts up to z = 2 by supplementing the optical survey COMBO-17 with observations in four near-infrared bands on 0.2 deg{sup 2} of the COMBO-17 A901-field. Our results are based on an H-band-selected catalog of 10,692 galaxies complete to H = 21fm7. We measure the rest-frame color (U{sub 280}-V) of each galaxy, which across the redshift range of our interest requires no extrapolation and is robust against moderate redshift errors by staying clear of the 4000 A break. We measure the color-magnitude relation of the red sequence as a function of look-back time from the peak in a color-error-weighted histogram, and thus trace the galaxy bimodality out to z {approx_equal} 1.65. The (U{sub 280}-V) of the red sequence is found to evolve almost linearly with look-back time. At high redshift, we find massive galaxies in both the red and the blue population. Red-sequence galaxies with log M{sub *}/M{sub sun}>11 increase in mass density by a factor of {approx}4 from z {approx} 2 to 1 and remain nearly constant at z < 1. However, some galaxies as massive as log M{sub *}/M{sub sun} = 11.5 are already in place at z {approx} 2.

  11. THE WHIQII SURVEY: METALLICITIES AND SPECTROSCOPIC PROPERTIES OF LUMINOUS COMPACT BLUE GALAXIES

    SciTech Connect

    Tollerud, Erik J.; Barton, Elizabeth J.; Cooke, Jeff; Van Zee, Liese

    2010-01-10

    As part of the WIYN High Image Quality Indiana-Irvine (WHIQII) survey, we present 123 spectra of faint emission-line galaxies, selected to focus on intermediate redshift (0.4 approx< z approx< 0.8) galaxies with blue colors that appear physically compact on the sky. The sample includes 15 true Luminous Compact Blue Galaxies (LCBGs) and an additional 27 slightly less extreme emission-line systems. These galaxies represent a highly evolving class that may play an important role in the decline of star formation since z approx 1, but their exact nature and evolutionary pathways remain a mystery. Here, we use emission lines to determine metallicities and ionization parameters, constraining their intrinsic properties and state of star formation. Some LCBG metallicities are consistent with a 'bursting dwarf' scenario, while a substantial fraction of others are not, further confirming that LCBGs are a highly heterogeneous population but are broadly consistent with the intermediate redshift field. In agreement with previous studies, we observe overall evolution in the luminosity-metallicity relation at intermediate redshift. Our sample, and particularly the LCBGs, occupies a region in the empirical R{sub 23}-O{sub 32} plane that differs from luminous local galaxies and is more consistent with dwarf irregulars at the present epoch, suggesting that cosmic 'downsizing' is observable in even the most fundamental parameters that describe star formation. These properties for our sample are also generally consistent with lying between local galaxies and those at high redshift, as expected by this scenario. Surprisingly, our sample exhibits no detectable correlation between compactness and metallicity, strongly suggesting that at these epochs of rapid star formation, the morphology of compact star-forming galaxies is largely transient.

  12. THE ADVANCED CAMERA FOR SURVEYS GENERAL CATALOG: STRUCTURAL PARAMETERS FOR APPROXIMATELY HALF A MILLION GALAXIES

    SciTech Connect

    Griffith, Roger L.; Kirkpatrick, J. Davy; Cooper, Michael C.; Newman, Jeffrey A.; Moustakas, Leonidas A.; Stern, Daniel; Comerford, Julia M.; Davis, Marc; Lotz, Jennifer M.; Koekemoer, Anton M.; Barden, Marco; Conselice, Christopher J.; Capak, Peter L.; Scoville, Nick; Sheth, Kartik; Shopbell, Patrick; Faber, S. M.; Koo, David C.; Willmer, Christopher N. A.; and others

    2012-05-01

    We present the Advanced Camera for Surveys General Catalog (ACS-GC), a photometric and morphological database using publicly available data obtained with the Advanced Camera for Surveys (ACS) instrument on the Hubble Space Telescope. The goal of the ACS-GC database is to provide a large statistical sample of galaxies with reliable structural and distance measurements to probe the evolution of galaxies over a wide range of look-back times. The ACS-GC includes approximately 470,000 astronomical sources (stars + galaxies) derived from the AEGIS, COSMOS, GEMS, and GOODS surveys. GALAPAGOS was used to construct photometric (SEXTRACTOR) and morphological (GALFIT) catalogs. The analysis assumes a single Sersic model for each object to derive quantitative structural parameters. We include publicly available redshifts from the DEEP2, COMBO-17, TKRS, PEARS, ACES, CFHTLS, and zCOSMOS surveys to supply redshifts (spectroscopic and photometric) for a considerable fraction ({approx}74%) of the imaging sample. The ACS-GC includes color postage stamps, GALFIT residual images, and photometry, structural parameters, and redshifts combined into a single catalog.

  13. Probing higher-order primordial non-Gaussianity with galaxy surveys

    NASA Astrophysics Data System (ADS)

    Yamauchi, Daisuke; Takahashi, Keitaro

    2016-06-01

    With a radio continuum galaxy survey by the Square Kilometre Array (SKA), a photometric galaxy survey by Euclid, and their combination, we forecast future constraints on primordial non-Gaussianity. We focus on the potential impact of local-type higher-order nonlinear parameters on the parameter estimation and particularly the confirmation of the inflationary consistency inequality. Nonstandard inflationary models, such as multifield models, introduce the scale-dependent stochastic clustering of galaxies on large scales, which is a unique probe of mechanism for generating primordial density fluctuations. Our Fisher matrix analysis indicates that a deep and wide survey provided by SKA is more advantageous to constrain τNL, while Euclid has a strong constraining power for fNL due to the redshift information, suggesting that the joint analysis between them is quite essential to break the degeneracy between the nonlinear parameters. The combination of the full SKA and Euclid will achieve the precision level needed to confirm the consistency inequality even for fNL≈1.5 and τNL≈17 , though it is still hard for a single survey to confirm it when fNL≲2.7 .

  14. The Bivariate Luminosity--HI Mass Distribution Function of Galaxies based on the NIBLES Survey

    NASA Astrophysics Data System (ADS)

    Butcher, Zhon; Schneider, Stephen E.; van Driel, Wim; Lehnert, Matt

    2016-01-01

    We use 21cm HI line observations for 2610 galaxies from the Nançay Interstellar Baryons Legacy Extragalactic Survey (NIBLES) to derive a bivariate luminosity--HI mass distribution function. Our HI survey was selected to randomly probe the local (900 < cz < 12,000 km/s) galaxy population in each 0.5 mag wide bin for the absolute z-band magnitude range of -13.5 < Mz < -24 without regard to morphology or color. This targeted survey allowed more on-source integration time for weak and non-detected sources, enabling us to probe lower HI mass fractions and apply lower upper limits for non-detections than would be possible with the larger blind HI surveys. Additionally, we obtained a factor of four higher sensitivity follow-up observations at Arecibo of 90 galaxies from our non-detected and marginally detected categories to quantify the underlying HI distribution of sources not detected at Nançay. Using the optical luminosity function and our higher sensitivity follow up observations as priors, we use a 2D stepwise maximum likelihood technique to derive the two dimensional volume density distribution of luminosity and HI mass in each SDSS band.

  15. The Herschel Virgo Cluster Survey. XVIII. Star-forming dwarf galaxies in a cluster environment

    NASA Astrophysics Data System (ADS)

    Grossi, M.; Hunt, L. K.; Madden, S. C.; Hughes, T. M.; Auld, R.; Baes, M.; Bendo, G. J.; Bianchi, S.; Bizzocchi, L.; Boquien, M.; Boselli, A.; Clemens, M.; Corbelli, E.; Cortese, L.; Davies, J.; De Looze, I.; di Serego Alighieri, S.; Fritz, J.; Pappalardo, C.; Pierini, D.; Rémy-Ruyer, A.; Smith, M. W. L.; Verstappen, J.; Viaene, S.; Vlahakis, C.

    2015-02-01

    To assess the effects of the cluster environment on the different components of the interstellar medium, we analyse the far-infrared (FIR) and submillimetre (submm) properties of a sample of star-forming dwarf galaxies detected by the Herschel Virgo Cluster Survey (HeViCS). We determine dust masses and dust temperatures by fitting a modified black body function to the spectral energy distributions (SEDs). Stellar and gas masses, star formation rates (SFRs), and metallicities are obtained from the analysis of a set of ancillary data. Dust is detected in 49 out of a total 140 optically identified dwarfs covered by the HeViCS field; considering only dwarfs brighter than mB = 18 mag, this gives a detection rate of 43%. After evaluating different emissivity indices, we find that the FIR-submm SEDs are best-fit by β = 1.5, with a median dust temperature Td = 22.4 K. Assuming β = 1.5, 67% of the 23 galaxies detected in all five Herschel bands show emission at 500 μm in excess of the modified black-body model. The fraction of galaxies with a submillimetre excess decreases for lower values of β, while a similarly high fraction (54%) is found if a β-free SED modelling is applied. The excess is inversely correlated with SFR and stellar masses. To study the variations in the global properties of our sample that come from environmental effects, we compare the Virgo dwarfs to other Herschel surveys,such as the Key Insights into Nearby Galaxies: Far-Infrared Survey with Herschel (KINGFISH), the Dwarf Galaxy Survey (DGS), and the HeViCS Bright Galaxy Catalogue (BGC). We explore the relations between stellar mass and Hi fraction, specific star formation rate, dust fraction, gas-to-dust ratio over a wide range of stellar masses (from 107 to 1011 M⊙) for both dwarfs and spirals. Highly Hi-deficient Virgo dwarf galaxies are mostly characterised by quenched star formation activity and lower dust fractions giving hints for dust stripping in cluster dwarfs. However, to explain the

  16. Status of The Dynamical Census of Galaxies and Groups in the RESOLVE Survey

    NASA Astrophysics Data System (ADS)

    Eckert, Kathleen D.; Kannappan, Sheila; Hall, Kirsten; Moffett, Amanda J.; Norris, Mark A.; Stark, David; Hoversten, Erik A.; Snyder, Elaine M.; Bittner, Ashley; Norman, Dara J.; Naluminsa, Elizabeth; Crawford, Steve; Vaisanen, Petri; Baker, Ashley; Berlind, Andreas A.; Rosenberg, Daniel; Beauchemin, Ryan William; Bonfield, Charles; RESOLVE Team

    2016-01-01

    The REsolved Spectroscopy of a Local VolumE (RESOLVE) survey is measuring either velocity dispersions or rotation velocities for ~1500 galaxies and ~200 multi-galaxy groups within >50,000 cubic Mpc of the z~0 universe, above a galaxy baryonic mass limit of ~10^9 Msun. Our kinematic census combines multi-slit, IFU, Fabry-Perot, long-slit, and radio linewidth data from the SOAR, SALT, Gemini, AAT, GBT, and Arecibo telescopes, with telescope/instrument combinations optimized for individual galaxy properties. We present a status update of the data taken, particularly focusing on the RESOLVE Early Science region overlapping Stripe 82. We also discuss challenges for dynamical measurements including measuring galaxy inclinations, determining the mix of support from rotational and random motions, and measuring dynamical masses for groups with few members. Finally, we conclude with a preliminary velocity function for the RESOLVE Early Science region. This work has been supported by the NSF through grants AST-0955368 and OCI-1156614, the NC Space Grant Graduate Research Fellowship Program, and a UNC Royster Society of Fellows Dissertation Completion Fellowship.

  17. Deep Photometry of Galaxies in the VEGAS Survey: The Case of NGC 4472

    NASA Astrophysics Data System (ADS)

    Spavone, M.

    The VST-VEGAS project is aimed at observing and studying a rich sample of nearby early-type galaxies in order to systematically characterize their properties over a wide baseline of sizes and out to the faint outskirts where data are rather scarce so far. The external regions of galaxies more easily retain signatures about the formation and evolution mechanisms which shaped them, as their relaxation time are longer, and they are more weakly influenced by processes such as mergers, secular evolution, central black hole activity, and supernova feedback on the ISM, which tend to level age and metallicity gradients. The collection of a wide photometric dataset of a large number of galaxies in various environmental conditions, may help to shed light on these questions. To this end VEGAS exploits the potential of the VLT Survey Telescope (VST) which provides high quality images of 1 deg2 field of view in order to satisfy both the requirement of high resolution data and the need of studying nearby, and thus large, objects. We present a detailed study of the surface photometry of the elliptical galaxy NGC4472 and of smaller ETGs in its field, performed by using new g and i bands images to constrain the formation history of this nearby giant galaxy, and to investigate the presence of very faint substructures in its surroundings.

  18. A Kepler Galaxy Survey: Establishing the Temporal Baseline for Extragalactic Systems

    NASA Astrophysics Data System (ADS)

    Fanelli, Michael

    Kepler's combination of high-photometric precision and near-continuous observing cadence permits a new, unique insight on galaxies, by opening up the time domain in previously unavailable detail. We propose to investigate ~1000 individual light curves of galaxies observed by Kepler during Q1-6. The proposed survey will be sensitive to both continuous variability, especially low-level variations from embedded active nuclei and random episodic events, such as supernovae. Our primary objectives are (a) to explore the photometric baseline of galactic systems over a range of amplitudes and timescales, (b) quantify the existence and amplitude of AGN signals in galaxy cores, (c) provide a direct measure of supernovae rates across galaxy types, complementary to ground-based supernova searches, and (d) quantify the early brightening of supernova as the explosion rises to peak luminosity. These data will provide a first look at the temporal behavior of extragalactic investigations. The Kepler data will be combined into a Galaxy Legacy Archive which will contain morphological and photometric parameters for the sources, the observing logs and photometric statistics derived from the light curves. An associated software IDL toolkit for Kepler data analysis will also be developed.

  19. A Photometric redshift galaxy catalog from the Red-Sequence Cluster Survey

    SciTech Connect

    Hsieh, Bau-Ching; Yee, H.K.C.; Lin, H.; Gladders, M.D.; /Carnegie Inst. Observ.

    2005-02-01

    The Red-Sequence Cluster Survey (RCS) provides a large and deep photometric catalog of galaxies in the z' and R{sub c} bands for 90 square degrees of sky, and supplemental V and B data have been obtained for 33.6 deg{sup 2}. They compile a photometric redshift catalog from these 4-band data by utilizing the empirical quadratic polynomial photometric redshift fitting technique in combination with CNOC2 and GOODS/HDF-N redshift data. The training set includes 4924 spectral redshifts. The resulting catalog contains more than one million galaxies with photometric redshifts < 1.5 and R{sub c} < 24, giving an rms scatter {delta}({Delta}z) < 0.06 within the redshift range 0.2 < z < 0.5 and {sigma}({Delta}z) < 0.11 for galaxies at 0.0 < z < 1.5. They describe the empirical quadratic polynomial photometric redshift fitting technique which they use to determine the relation between red-shift and photometry. A kd-tree algorithm is used to divide up the sample to improve the accuracy of the catalog. They also present a method for estimating the photometric redshift error for individual galaxies. They show that the redshift distribution of the sample is in excellent agreement with smaller and much deeper photometric and spectroscopic redshift surveys.

  20. Systematic Survey of the Correlation between Northern HECR Events and SDSS Galaxies

    NASA Astrophysics Data System (ADS)

    Takami, H.; Nishimichi, T.; Sato, K.

    2011-12-01

    We investigated the spatial correlation between the arrival directions of the highest energy cosmic rays (HECRs) detected by the Akeno Giant Air Shower Array (AGASA) with energies above 4 × 10^{19} eV and the positions of galaxies observed by the Sloan Digital Sky Survey (SDSS) within z = 0.024. We systematically tested the dependence of the correlation on the redshift ranges and properties of the galaxies, i.e., absolute luminosity, color, and morphology, to understand where HECR sources are and what objects are HECR sources. In the systematic survey, we found potential signals of the positive correlation at small angular scale (< 10°) with the (non-penalized) chance probability less than 5% in intermediate redshift ranges. Then, we estimated penalized probabilities to compensate the trial effects of angular scan, and found that the strongest correlation is produced by early-type galaxies in 0.012 ≤ z < 0.018 at 90% C.L. The possible origin of HECRs which correlating galaxies imply is also discussed.

  1. The Cambridge-Cambridge X-ray Serendipity Survey: I X-ray luminous galaxies

    NASA Technical Reports Server (NTRS)

    Boyle, B. J.; Mcmahon, R. G.; Wilkes, B. J.; Elvis, M.

    1994-01-01

    We report on the first results obtained from a new optical identification program of 123 faint X-ray sources with S(0.5-2 keV) greater than 2 x 10(exp -14) erg/s/sq cm serendipitously detected in ROSAT PSPC pointed observations. We have spectroscopically identified the optical counterparts to more than 100 sources in this survey. Although the majority of the sample (68 objects) are QSO's, we have also identified 12 narrow emission line galaxies which have extreme X-ray luminosities (10(exp 42) less than L(sub X) less than 10(exp 43.5) erg/s). Subsequent spectroscopy reveals them to be a mixture of star-burst galaxies and Seyfert 2 galaxies in approximately equal numbers. Combined with potentially similar objects identified in the Einstein Extended Medium Sensitivity Survey, these X-ray luminous galaxies exhibit a rate of cosmological evolution, L(sub X) varies as (1 + z)(exp 2.5 +/- 1.0), consistent with that derived for X-ray QSO's. This evolution, coupled with the steep slope determined for the faint end of the X-ray luminosity function (Phi(L(sub X)) varies as L(sub X)(exp -1.9)), implies that such objects could comprise 15-35% of the soft (1-2 keV) X-ray background.

  2. Ultra-compact high velocity clouds in the ALFALFA HI survey: Candidate Local Group galaxies?

    NASA Astrophysics Data System (ADS)

    Adams, Elizabeth Ann Kovenz

    The increased sensitivity and spatial resolution of the ALFALFA HI survey has resulted in the detection of ultra-compact high velocity clouds (UCHVCs). These objects are good candidates to represent low mass gas-rich galaxies in the Local Group and Local Volume with stellar populations that are too faint to be detected in extant optical surveys. This idea is referred to as the "minihalo hypothesis". We identify the UCHVCs within the ALFALFA dataset via the use of a 3D matched filtering signal identification algorithm. UCHVCs are selected based on a compact size (< 30'), separation from Galactic HI (|upsilon LSR| > 120 km s-1) and isolation. Within the 40% complete ALFALFA survey (alpha.40), 59 UCHVCs are identified; 19 are in a most-isolated subset and are the best galaxy candidates. Due to the presence of large HVC complexes in the fall sky, most notably the Magellanic Stream, the association of UCHVCs with existing structure cannot be ruled out. In the spring sky, the spatial and kinematic distribution of the UCHVCs is consistent with simulations of dark matter halos within the Local Group. In addition, the HI properties of the UCHVCs (if placed at 1 Mpc) are consistent with both theoretical and observational predictions for low mass gas-rich galaxies. Importantly, the HI properties of the UCHVCs are consistent with those of two recently discovered low mass gas-rich galaxies in the Local Group and Local Volume, Leo T and Leo P. Detailed follow-up observations are key for addressing the minihalo hypothesis. High resolution HI observations can constrain the environment of a UCHVC and offer evidence for a hosting dark matter halo through evidence of rotation support and comparison to theoretical models. Observations of one UCHVC at high resolution (15'') reveal the presence of a clumpy HI distribution, similar to both low mass galaxies and circumgalactic compact HVCs. An extended envelope containing ˜50% of the HI flux is resolved out by the array configuration

  3. Luminosity dependence of the spatial and velocity distributions of galaxies: semi-analytic models versus the Sloan Digital Sky Survey

    NASA Astrophysics Data System (ADS)

    Li, Cheng; Jing, Y. P.; Kauffmann, Guinevere; Börner, Gerhard; Kang, Xi; Wang, Lan

    2007-04-01

    By comparing semi-analytic galaxy catalogues with data from the Sloan Digital Sky Survey (SDSS), we show that current galaxy formation models reproduce qualitatively the dependence of galaxy clustering and pairwise peculiar velocities on luminosity, but some subtle discrepancies with the data still remain. The comparisons are carried out by constructing a large set of mock galaxy redshift surveys that have the same selection function as the SDSS Data Release Four (DR4). The mock surveys are based on two sets of semi-analytic catalogues presented by Croton et al. and Kang et al. From the mock catalogues, we measure the redshift-space projected two-point correlation function wp(rp), the power spectrum P(k) and the pairwise velocity dispersion (PVD) in Fourier space σ12(k) and in configuration space σ12(rp), for galaxies in different luminosity intervals. We then compare these theoretical predictions with the measurements derived from the SDSS DR4. On large scales and for galaxies brighter than L*, both sets of mock catalogues agree well with the data. For fainter galaxies, however, both models predict stronger clustering and higher pairwise velocities than observed. We demonstrate that this problem can be resolved if the fraction of faint satellite galaxies in massive haloes is reduced by ~30 per cent compared to the model predictions. A direct look into the model galaxy catalogues reveals that a significant fraction (15 per cent) of faint galaxies (-18 < M0.1r - 5 log10h < -17) reside in haloes with Mvir > 1013 Msolar, and this population is predominantly red in colour. These faint red galaxies are responsible for the high PVD values of low-luminosity galaxies on small scales.

  4. FIRST RESULTS FROM THE 3D-HST SURVEY: THE STRIKING DIVERSITY OF MASSIVE GALAXIES AT z > 1

    SciTech Connect

    Van Dokkum, Pieter G.; Nelson, Erica; Skelton, Rosalind E.; Bezanson, Rachel; Lundgren, Britt; Brammer, Gabriel; Fumagalli, Mattia; Franx, Marijn; Patel, Shannon; Labbe, Ivo; Rix, Hans-Walter; Schmidt, Kasper B.; Da Cunha, Elisabete; Kriek, Mariska; Bian Fuyan; Fan Xiaohui; Erb, Dawn K.; Foerster Schreiber, Natascha; Illingworth, Garth D.; Magee, Dan; and others

    2011-12-10

    We present first results from the 3D-HST program, a near-IR spectroscopic survey performed with the Wide Field Camera 3 (WFC3) on the HST. We have used 3D-HST spectra to measure redshifts and H{alpha} equivalent widths (EW{sub H{alpha}}) for a complete, stellar mass-limited sample of 34 galaxies at 1 < z < 1.5 with M{sub star} > 10{sup 11} M{sub Sun} in the COSMOS, GOODS, and AEGIS fields. We find that a substantial fraction of massive galaxies at this epoch are forming stars at a high rate: the fraction of galaxies with EW{sub H{alpha}} >10 A is 59%, compared to 10% among Sloan Digital Sky Survey galaxies of similar masses at z = 0.1. Galaxies with weak H{alpha} emission show absorption lines typical of 2-4 Gyr old stellar populations. The structural parameters of the galaxies, derived from the associated WFC3 F140W imaging data, correlate with the presence of H{alpha}; quiescent galaxies are compact with high Sersic index and high inferred velocity dispersion, whereas star-forming galaxies are typically large two-armed spiral galaxies, with low Sersic index. Some of these star-forming galaxies might be progenitors of the most massive S0 and Sa galaxies. Our results challenge the idea that galaxies at fixed mass form a homogeneous population with small scatter in their properties. Instead, we find that massive galaxies form a highly diverse population at z > 1, in marked contrast to the local universe.

  5. Very deep IRAS survey - constraints on the evolution of starburst galaxies

    SciTech Connect

    Hacking, P.; Houck, J.R.; Condon, J.J.

    1987-05-01

    Counts of sources (primarily starburst galaxies) from a deep 60 microns IRAS survey published by Hacking and Houck (1987) are compared with four evolutionary models. The counts below 100 mJy are higher than expected if no evolution has taken place out to a redshift of approximately 0.2. Redshift measurements of the survey sources should be able to distinguish between luminosity-evolution and density-evolution models and detect as little as a 20 percent brightening or increase in density of infrared sources per billion years ago (H/0/ = 100 km/s per Mpc). Starburst galaxies cannot account for the reported 100 microns background without extreme evolution at high redshifts. 21 references.

  6. A very deep IRAS survey - Constraints on the evolution of starburst galaxies

    NASA Astrophysics Data System (ADS)

    Hacking, Perry; Condon, J. J.; Houck, J. R.

    1987-05-01

    Counts of sources (primarily starburst galaxies) from a deep 60 microns IRAS survey published by Hacking and Houck (1987) are compared with four evolutionary models. The counts below 100 mJy are higher than expected if no evolution has taken place out to a redshift of approximately 0.2. Redshift measurements of the survey sources should be able to distinguish between luminosity-evolution and density-evolution models and detect as little as a 20 percent brightening or increase in density of infrared sources per billion years ago (H/0/ = 100 km/s per Mpc). Starburst galaxies cannot account for the reported 100 microns background without extreme evolution at high redshifts.

  7. Semi-analytic models for the CANDELS survey: comparison of predictions for intrinsic galaxy properties

    SciTech Connect

    Lu, Yu; Wechsler, Risa H.; Somerville, Rachel S.; Croton, Darren; Porter, Lauren; Primack, Joel; Moody, Chris; Behroozi, Peter S.; Ferguson, Henry C.; Koo, David C.; Guo, Yicheng; Finlator, Kristian; Castellano, Marco; Sommariva, Veronica E-mail: rwechsler@stanford.edu

    2014-11-10

    We compare the predictions of three independently developed semi-analytic galaxy formation models (SAMs) that are being used to aid in the interpretation of results from the CANDELS survey. These models are each applied to the same set of halo merger trees extracted from the 'Bolshoi' high-resolution cosmological N-body simulation and are carefully tuned to match the local galaxy stellar mass function using the powerful method of Bayesian Inference coupled with Markov Chain Monte Carlo or by hand. The comparisons reveal that in spite of the significantly different parameterizations for star formation and feedback processes, the three models yield qualitatively similar predictions for the assembly histories of galaxy stellar mass and star formation over cosmic time. Comparing SAM predictions with existing estimates of the stellar mass function from z = 0-8, we show that the SAMs generally require strong outflows to suppress star formation in low-mass halos to match the present-day stellar mass function, as is the present common wisdom. However, all of the models considered produce predictions for the star formation rates (SFRs) and metallicities of low-mass galaxies that are inconsistent with existing data. The predictions for metallicity-stellar mass relations and their evolution clearly diverge between the models. We suggest that large differences in the metallicity relations and small differences in the stellar mass assembly histories of model galaxies stem from different assumptions for the outflow mass-loading factor produced by feedback. Importantly, while more accurate observational measurements for stellar mass, SFR and metallicity of galaxies at 1 < z < 5 will discriminate between models, the discrepancies between the constrained models and existing data of these observables have already revealed challenging problems in understanding star formation and its feedback in galaxy formation. The three sets of models are being used to construct catalogs of mock

  8. EXTENDED PHOTOMETRY FOR THE DEEP2 GALAXY REDSHIFT SURVEY: A TESTBED FOR PHOTOMETRIC REDSHIFT EXPERIMENTS

    SciTech Connect

    Matthews, Daniel J.; Newman, Jeffrey A.; Coil, Alison L.; Cooper, Michael C.; Gwyn, Stephen D. J. E-mail: janewman@pitt.edu E-mail: m.cooper@uci.edu

    2013-02-15

    This paper describes a new catalog that supplements the existing DEEP2 Galaxy Redshift Survey photometric and spectroscopic catalogs with ugriz photometry from two other surveys: the Canada-France-Hawaii Legacy Survey (CFHTLS) and the Sloan Digital Sky Survey (SDSS). Each catalog is cross-matched by position on the sky in order to assign ugriz photometry to objects in the DEEP2 catalogs. We have recalibrated the CFHTLS photometry where it overlaps DEEP2 in order to provide a more uniform data set. We have also used this improved photometry to predict DEEP2 BRI photometry in regions where only poorer measurements were available previously. In addition, we have included improved astrometry tied to SDSS rather than USNO-A2.0 for all DEEP2 objects. In total this catalog contains {approx}27, 000 objects with full ugriz photometry as well as robust spectroscopic redshift measurements, 64% of which have r > 23. By combining the secure and accurate redshifts of the DEEP2 Galaxy Redshift Survey with ugriz photometry, we have created a catalog that can be used as an excellent testbed for future photo-z studies, including tests of algorithms for surveys such as LSST and DES.

  9. A deep redshift survey of field galaxies. Comments on the reality of the Butcher-Oemler effect

    NASA Technical Reports Server (NTRS)

    Koo, David C.; Kron, Richard G.

    1987-01-01

    A spectroscopic survey of over 400 field galaxies has been completed in three fields for which we have deep UBVI photographic photometry. The galaxies typically range from B=20 to 22 and possess redshifts z from 0.1 to 0.5 that are often quite spiky in distribution. Little, if any, luminosity evolution is observed up to redshifts z approx 0.5. By such redshifts, however, an unexpectedly large fraction of luminous galaxies has very blue intrinsic colors that suggest extensive star formation; in contrast, the reddest galaxies still have colors that match those of present-day ellipticals.

  10. Local SDSS galaxies in the Herschel Stripe 82 survey: a critical assessment of optically derived star formation rates

    NASA Astrophysics Data System (ADS)

    Rosario, D. J.; Mendel, J. T.; Ellison, S. L.; Lutz, D.; Trump, J. R.

    2016-04-01

    We study a set of 3319 galaxies in the redshift interval 0.04 < z < 0.15 with far-infrared (FIR) coverage from the Herschel Stripe 82 survey (HerS), and emission-line measurements, redshifts, stellar masses and star formation rates (SFRs) from the Sloan Digital Sky Survey (SDSS) (DR7) MPA/JHU data base. About 40 per cent of the sample are detected in the Herschel/SPIRE 250 μm band. Total infrared (TIR) luminosities derived from HerS and Wide-field Infrared Survey Explorer (WISE) photometry allow us to compare infrared and optical estimates of SFR with unprecedented statistics for diverse classes of galaxies. We find excellent agreement between TIR-derived and emission line-based SFRs for H II galaxies. Other classes, such as active galaxies and evolved galaxies, exhibit systematic discrepancies between optical and TIR SFRs. We demonstrate that these offsets are attributable primarily to survey biases and the large intrinsic uncertainties of the Dn4000- and colour-based optical calibrations used to estimate the SDSS SFRs of these galaxies. Using a classification scheme which expands upon popular emission-line methods, we demonstrate that emission-line galaxies with uncertain classifications include a population of massive, dusty, metal-rich star-forming systems that are frequently neglected in existing studies. We also study the capabilities of infrared selection of star-forming galaxies. FIR selection reveals a substantial population of galaxies dominated by cold dust which are missed by the long-wavelength WISE bands. Our results demonstrate that Herschel large-area surveys offer the means to construct large, relatively complete samples of local star-forming galaxies with accurate estimates of SFR that can be used to study the interplay between nuclear activity and star formation.

  11. Galaxy interactions and star formation: Results of a survey of global H-alpha emission in spiral galaxies in 8 clusters

    NASA Technical Reports Server (NTRS)

    Moss, C.

    1990-01-01

    Kennicutt and Kent (1983) have shown that the global H alpha emission from a spiral galaxy is an indicator of the formation rate of massive stars. Moss, Whittle and Irwin (1988) have surveyed two clusters (Abell 347 and 1367) for galaxies with H alpha emission using a high dispersion objective prism technique. The purpose of the survey is to investigate environmental effects on star formation in spiral galaxies, and in particular to ascertain whether star formation is enhanced in cluster spirals. Approximately 20 percent of CGCG galaxies were detected in emission. Two plates of excellent quality were obtained for each of the two clusters, and galaxies were only identified to have emission if this was detected on both plates of a plate pair. In this way, plate flaws and other spurious identifications of emission could be rejected, and weak emission confirmed. The results of this survey have been discussed by Moss (1987). The detected galaxies are of types SO-a and later. The frequency with which galaxies are detected in emission increases towards later morphological type as expected (cf. Kennicutt and Kent 1983). There is no evidence of any dependence of the frequency of detected emission on the absolute magnitude of the galaxy (cf. Moss and Whittle 1990), but there is a strong correlation between a disturbed morphological appearance of the galaxy and the detection of emission. Furthermore it is found that the emission is more centrally concentrated in those galaxies which show a disturbed morphology. It may be noted that the objective prism plate gives a spectrum of a 400 A region around rest wavelength H alpha, but superposed on this is the H alpha emission from the galaxy which, because the light is essentially monochromatic, results in a true two-dimensional image of the H alpha distribution. The visual appearance of the emission on the prism plates was classified according to its diffuseness on a 5 point scale (very diffuse, diffuse, intermediate, compact, and

  12. Explained: Why many surveys of distant galaxies miss 90% of their targets

    NASA Astrophysics Data System (ADS)

    2010-03-01

    Astronomers have long known that in many surveys of the very distant Universe, a large fraction of the total intrinsic light was not being observed. Now, thanks to an extremely deep survey using two of the four giant 8.2-metre telescopes that make up ESO's Very Large Telescope (VLT) and a unique custom-built filter, astronomers have determined that a large fraction of galaxies whose light took 10 billion years to reach us have gone undiscovered. The survey also helped uncover some of the faintest galaxies ever found at this early stage of the Universe. Astronomers frequently use the strong, characteristic "fingerprint" of light emitted by hydrogen known as the Lyman-alpha line, to probe the amount of stars formed in the very distant Universe [1]. Yet there have long been suspicions that many distant galaxies go unnoticed in these surveys. A new VLT survey demonstrates for the first time that this is exactly what is happening. Most of the Lyman-alpha light is trapped within the galaxy that emits it, and 90% of galaxies do not show up in Lyman-alpha surveys. "Astronomers always knew they were missing some fraction of the galaxies in Lyman-alpha surveys," explains Matthew Hayes, the lead author of the paper, published this week in Nature, "but for the first time we now have a measurement. The number of missed galaxies is substantial." To figure out how much of the total luminosity was missed, Hayes and his team used the FORS camera at the VLT and a custom-built narrowband filter [2] to measure this Lyman-alpha light, following the methodology of standard Lyman-alpha surveys. Then, using the new HAWK-I camera, attached to another VLT Unit Telescope, they surveyed the same area of space for light emitted at a different wavelength, also by glowing hydrogen, and known as the H-alpha line. They specifically looked at galaxies whose light has been travelling for 10 billion years (redshift 2.2 [3]), in a well-studied area of the sky, known as the GOODS-South field. "This is

  13. Testing cosmology with a catalogue of voids in the BOSS galaxy surveys

    NASA Astrophysics Data System (ADS)

    Nadathur, Seshadri

    2016-09-01

    We present a public catalogue of voids in the Baryon Oscillation Spectroscopic Survey (BOSS) Data Release 11 LOWZ and CMASS galaxy surveys. This catalogue contains information on the location, sizes, densities, shapes and bounding surfaces of 8956 independent, disjoint voids, making it the largest public void catalogue to date. Voids are identified using a version of the ZOBOV algorithm, the operation of which has been calibrated though tests on mock galaxy populations in N-body simulations, as well as on a suite of 4096 mock catalogues which fully reproduce the galaxy clustering, survey masks and selection functions. Based on this, we estimate a false positive detection rate of 3 per cent. Comparison with mock catalogues limits deviations of the void size distribution from that predicted in the ΛCDM model to be less than 6 per cent for voids with effective radius 8 < Rv < 60 h-1Mpc and in the redshift range 0.15 < z < 0.7. This could tightly constrain modified gravity scenarios and models with a varying equation of state, but we identify systematic biases which must be accounted for to reduce the theoretical uncertainty in the predictions for these models to the current level of precision attained from the data. We also examine the distribution of void densities and identify a deficit of the deepest voids relative to ΛCDM expectations, which is significant at more than the 3σ equivalent level. We discuss possible explanations for this discrepancy but at present its cause remains unknown.

  14. Neutrino constraints from future nearly all-sky spectroscopic galaxy surveys

    SciTech Connect

    Carbone, Carmelita; Cimatti, Andrea; Verde, Licia; Wang, Yun E-mail: liciaverde@icc.ub.edu E-mail: a.cimatti@unibo.it

    2011-03-01

    We examine whether future, nearly all-sky galaxy redshift surveys, in combination with CMB priors, will be able to detect the signature of the cosmic neutrino background and determine the absolute neutrino mass scale. We also consider what constraints can be imposed on the effective number of neutrino species. In particular we consider two spectroscopic strategies in the near-IR, the so-called ''slitless'' and ''multi-slit'' approaches, whose examples are given by future space-based galaxy surveys, as EUCLID for the slitless case, or SPACE, JEDI, and possibly WFIRST in the future, for the multi-slit case. We find that, in combination with Planck, these galaxy probes will be able to detect at better than 3-sigma level and measure the mass of cosmic neutrinos: a) in a cosmology-independent way, if the sum of neutrino masses is above 0.1 eV; b) assuming spatial flatness and that dark energy is a cosmological constant, otherwise. We find that the sensitivity of such surveys is well suited to span the entire range of neutrino masses allowed by neutrino oscillation experiments, and to yield a clear detection of non-zero neutrino mass. The detection of the cosmic relic neutrino background with cosmological experiments will be a spectacular confirmation of our model for the early Universe and a window into one of the oldest relic components of our Universe.

  15. Surveying Massive Star Formation in the Inner Galaxy

    NASA Astrophysics Data System (ADS)

    Dorda, R.; Negueruela, I.; González-Fernández, C.; Marco, A.

    2016-10-01

    The base of the Scutum arm is a Galactic region with a high density of red supergiant (RSG) stars, grouped in a few clusters which have similar ages, positions and radial velocities. We have performed an extensive survey using the multi-object spectrograph AAOmega, looking for new RSGs along the galactic plane from l˜24° to 30°. We have observed >1600 candidates, and identified them through an extensive study of the statistical behavior of RSG spectra, finding ˜200 new RSGs.

  16. An analysis of a full sky redshift survey of IRAS galaxies

    NASA Astrophysics Data System (ADS)

    Fisher, Karl Booth

    1992-01-01

    Results are presented from an all-sky redshift survey of 5307 galaxies extracted from the Infrared Astronomical Satellite (IRAS) Point Source Catalog. The analysis presented in this thesis focuses on the spatial distribution and clustering of IRAS galaxies in this survey. We present an in-depth analysis of the possibility of density evolution in the catalogue. We conclude that the 1.2 Jy IRAS survey is consistent with no evolution, if the comoving density of galaxies is characterized as evolving proportional to (1 + z)alpha, we find alpha = 2 +/- 3, where the quoted error includes both random and systematic components. The random errors in alpha, of order 2, arise primarily from counting statistics, and are comparable to those found by previous authors. We discuss a variety of important random and systematic errors which decrease the certainty with which we can measure evolution: limited knowledge of the cosmological model, the unknown intrinsic spectral energy distribution of IRAS galaxies from 16 to 140 mu m, the effect of density fluctuations, a Malmquist-like bias arising from flux errors in the parent IRAS Point Source Catalog, and possible incompleteness of the sample at high redshifts and low Galactic latitudes. We show that the Malmquist bias could result in a significant overestimation of the evolution rate, especially if the catalog has a flux limit near the completion limit of the Point Source Catalog. We examine the two-point correlation function of the sample in both real and redshift space. The redshift space correlation function, xi(s), is shown to be robust and independent of the depth of the sample in which it is computed. We have also computed the Fourier conjugate of the correlation function, the power spectrum of galaxy clustering, P(k), for the 1.2 Jy IRAS survey using a window function which minimizes the aliasing due to the sample boundaries. We compare the IRAS power spectrum qualitatively with a variety of theoretical models, and conclude

  17. THE SINS/zC-SINF SURVEY of z {approx} 2 GALAXY KINEMATICS: OUTFLOW PROPERTIES

    SciTech Connect

    Newman, Sarah F.; Genzel, Reinhard; Foerster-Schreiber, Natascha M.; Buschkamp, Peter; Davies, Ric; Eisenhauer, Frank; Kurk, Jaron; Lutz, Dieter; Griffin, Kristen Shapiro; Mancini, Chiara; Renzini, Alvio; Lilly, Simon J.; Carollo, C. Marcella; Peng, Yingjie; Bouche, Nicolas; Burkert, Andreas; Cresci, Giovanni; Genel, Shy; Hicks, Erin K. S.; Naab, Thorsten; and others

    2012-12-10

    Using SINFONI H{alpha}, [N II], and [S II] AO data of 27 z {approx} 2 star-forming galaxies (SFGs) from the SINS and zC-SINF surveys, we explore the dependence of outflow strength (via the broad flux fraction) on various galaxy parameters. For galaxies that have evidence for strong outflows, we find that the broad emission is spatially extended to at least the half-light radius ({approx}a few kpc). Decomposition of the [S II] doublet into broad and narrow components suggests that this outflowing gas probably has a density of {approx}10-100 cm{sup -3}, less than that of the star-forming gas (600 cm{sup -3}). There is a strong correlation of the H{alpha} broad flux fraction with the star formation surface density of the galaxy, with an apparent threshold for strong outflows occurring at 1 M{sub Sun} yr{sup -1} kpc{sup -2}. Above this threshold, we find that SFGs with log m{sub *} > 10 have similar or perhaps greater wind mass-loading factors ({eta} = M-dot{sub out}/SFR) and faster outflow velocities than lower mass SFGs, suggesting that the majority of outflowing gas at z {approx} 2 may derive from high-mass SFGs. The mass-loading factor is also correlated with the star formation rate (SFR), galaxy size, and inclination, such that smaller, more star-forming, and face-on galaxies launch more powerful outflows. We propose that the observed threshold for strong outflows and the observed mass loading of these winds can be explained by a simple model wherein break-out of winds is governed by pressure balance in the disk.

  18. The Keck OSIRIS Nearby AGN Survey: Tracing Inflow within the Central 200 pc of Seyfert Galaxies

    NASA Astrophysics Data System (ADS)

    Hicks, Erin K. S.; Müller-Sánchez, Francisco; Malkan, Matthew A.; Yu, Po-Chieh

    2016-08-01

    In an effort to identify the fundamental processes driving feeding and feedback in AGN we turn to local Seyfert galaxies and rely on a multi-wavelength approach. With the integral field unit OSIRIS and adaptive optics we characterize the nuclear stars and gas down to scales of 5-30 parsecs in a sample of 40 Seyfert galaxies with the Keck OSIRIS Nearby AGN (KONA) survey. The complex gas kinematics in these near-IR data are interpreted using an integrative approach through comparison with data available at a range of wavelengths. We present first results from the survey with a focus on work aimed at constraining the mechanism(s) driving inflow of material within the central 200 pc. Particularly useful in the identification of inflow mechanisms (e.g. nuclear spiral, external accretion) is spatial correlation of the molecular gas distribution and kinematics with dust features revealed in HST imaging (optical and near-IR). Also informative is comparison with X-ray emission to identify locations likely influenced by interactions with outflows. The stellar kinematics in the sample galaxies (traced by CO bandheads at 2.3 microns) indicate a stellar population within the central few 100 parsecs in circular rotation, and in the majority of the galaxies the molecular gas (traced by H2 emission at 2.1218 microns) is found to have a rotating component co-spatial with the stellar disk. A significant fraction of the galaxies also exhibit kinematic signatures of inflow superimposed on this disk rotation, with inflow driven by secular and non-secular processes identified. We explore statistical trends of the nuclear stellar and molecular gas properties, including primary fueling mechanism, with Seyfert type, AGN luminosity, and host environment with the goal of disentangling which properties are fundamental to the nature of the AGN.

  19. Shocked POststarburst Galaxy Survey. II. The Molecular Gas Content and Properties of a Subset of SPOGs

    NASA Astrophysics Data System (ADS)

    Alatalo, Katherine; Lisenfeld, Ute; Lanz, Lauranne; Appleton, Philip N.; Ardila, Felipe; Cales, Sabrina L.; Kewley, Lisa J.; Lacy, Mark; Medling, Anne M.; Nyland, Kristina; Rich, Jeffrey A.; Urry, C. Meg

    2016-08-01

    We present CO(1-0) observations of objects within the Shocked POststarburst Galaxy Survey taken with the Institut de Radioastronomie Millimétrique 30 m single dish and the Combined Array for Research for Millimeter Astronomy interferometer. Shocked poststarburst galaxies (SPOGs) represent a transitioning population of galaxies, with deep Balmer absorption ({{EW}}{{H}δ }\\gt 5 {\\mathring{{A}}} ), consistent with an intermediate-age (A-star) stellar population, and ionized gas line ratios inconsistent with pure star formation. The CO(1-0) subsample was selected from SPOGs detected by the Wide-field Infrared Survey Explorer with 22 μm flux detected at a signal-to-noise ratio (S/N) > 3. Of the 52 objects observed in CO(1-0), 47 are detected with S/N > 3. A large fraction (37%-46% ± 7%) of our CO-SPOG sample were visually classified as morphologically disrupted. The H2 masses detected were between {10}8.7-10.8 {M}⊙ , consistent with the gas masses found in normal galaxies, though approximately an order of magnitude larger than the range seen in poststarburst galaxies. When comparing the 22 μm and CO(1-0) fluxes, SPOGs diverge from the normal star-forming relation, having 22 μm fluxes in excess of the relation by a factor of < {ɛ }{{MIR}}> ={4.91}-0.39+0.42, suggestive of the presence of active galactic nuclei (AGNs). The Na i D characteristics of CO-SPOGs show that it is likely that many of these objects host interstellar winds. Objects with large Na i D enhancements also tend to emit in the radio, suggesting possible AGN driving of neutral winds.

  20. THE DEEP3 GALAXY REDSHIFT SURVEY: KECK/DEIMOS SPECTROSCOPY IN THE GOODS-N FIELD

    SciTech Connect

    Cooper, Michael C.; Aird, James A.; Coil, Alison L. E-mail: acoil@ucsd.edu

    2011-03-15

    We present the results of spectroscopic observations in the GOODS-N field completed using DEIMOS on the Keck II telescope as part of the DEEP3 Galaxy Redshift Survey. Observations of 370 unique targets down to a limiting magnitude of R {sub AB} = 24.4 yielded 156 secure redshifts. In addition to redshift information, we provide sky-subtracted one- and two-dimensional spectra of each target. Observations were conducted following the procedures of the Team Keck Redshift Survey (TKRS), thereby producing spectra that augment the TKRS sample while maintaining the uniformity of its spectral database.

  1. VizieR Online Data Catalog: Survey of Markarian galaxies (Bicay+ 1995)

    NASA Astrophysics Data System (ADS)

    Bicay, M. D.; Kojoian, G.; Seal, J.; Dickinson, D. F.; Malkan, M. A.

    1997-06-01

    Results are presented from a multifrequency radio continuum survey of Markarian galaxies (MRKs) and are supplemented by IRAS infrared data from the Faint Source Survey. Radio data are presented for 899 MRKs observed at ν=4.755GHz with the NRAO-Green Bank 300 foot (91m) telescope, including nearly 88% of those objects in Markarian list VI-XIV. In addition, 1.415GHz measurements of 258 MRKs, over 30% of the MRKs accessible from NAIC-Arecibo, are reported. Radio continuum observations of smaller numbers of MRKs were made at 10.63GHz and at 23.1GHz and are also presented. (5 data files).

  2. The Deep2 Galaxy Redshift Survey: Mean Ages and Metallicities ofRed Field Galaxies at Z ~; 0.9 from Stacked Keck/Deimos Spectra

    SciTech Connect

    Schiavon, Ricardo P.; Faber, S.M.; Konidaris, Nicholas; Graves,Genevieve; Willmer, Christopher N.A.; Weiner, Benjamin J.; Coil, AlisonL.; Cooper, Michael C.; Davis, Marc; Harker, Justin; Koo, David C.; Newman, Jeffrey A.; Yan, Renbin

    2006-10-19

    As part of the DEEP2 galaxy redshift survey, we analyze absorption line strengths in stacked Keck/DEIMOS spectra of red field galaxies with weak to no emission lines, at redshifts 0.7 {approx}< z {approx}< 1. Comparison with models of stellar population synthesis shows that red galaxies at z {approx} 0:9 have mean luminosity-weighted ages of the order of only 1 Gyr and at least solar metallicities. These ages cannot be reconciled with a scenario where all stars evolved passively after forming at very high z. Rather, a significant fraction of stars can be no more than 1 Gyr old, which means that some star formation in the stacked populations continued to at least z {approx} 1:2. Furthermore, a comparison of these distant galaxies with a local SDSS sample, using stellar populations synthesis models, shows that the drop in the equivalent width of H{delta} from z {approx} 0:9 to 0.1 is less than predicted by passively evolving models. This admits of two interpretations: either each individual galaxy experiences continuing low-level star formation, or the red-sequence galaxy population from z {approx} 0:9 to 0.1 is continually being added to by new galaxies with younger stars.

  3. Large Scale CO Survey of the Northern Galaxy

    NASA Astrophysics Data System (ADS)

    Jiang, Zhibo; Li, Junyu

    2013-07-01

    We present the 12CO, 13CO and C18O line survey towards a region of L=(13.2,16.3) and B=(-1.2, 0.2), as a part the ambitious project, the Milky Way Image Scroll Painting. The CO line emissions show a number of velocity components, each component shows different structure and morphology than the others. A common feature that shows up in every component is the filamentary structures. Meanwhile a number of bubbles are found in some components, which are especially clear at 40 km s-1 and 60 km s-1. The velocity gradient of the 20 km s-1 component is surprisingly large, which can be interpreted neither by simply assuming the global rotation of the spiral arms nor by assuming the local motion along the spiral arm.

  4. The Data Reduction Pipeline for the SDSS-IV MaNGA IFU Galaxy Survey

    NASA Astrophysics Data System (ADS)

    Law, David R.; Cherinka, Brian; Yan, Renbin; Andrews, Brett H.; Bershady, Matthew A.; Bizyaev, Dmitry; Blanc, Guillermo A.; Blanton, Michael R.; Bolton, Adam S.; Brownstein, Joel R.; Bundy, Kevin; Chen, Yanmei; Drory, Niv; D'Souza, Richard; Fu, Hai; Jones, Amy; Kauffmann, Guinevere; MacDonald, Nicholas; Masters, Karen L.; Newman, Jeffrey A.; Parejko, John K.; Sánchez-Gallego, José R.; Sánchez, Sebastian F.; Schlegel, David J.; Thomas, Daniel; Wake, David A.; Weijmans, Anne-Marie; Westfall, Kyle B.; Zhang, Kai

    2016-10-01

    Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) is an optical fiber-bundle integral-field unit (IFU) spectroscopic survey that is one of three core programs in the fourth-generation Sloan Digital Sky Survey (SDSS-IV). With a spectral coverage of 3622-10354 Å and an average footprint of ˜500 arcsec2 per IFU the scientific data products derived from MaNGA will permit exploration of the internal structure of a statistically large sample of 10,000 low-redshift galaxies in unprecedented detail. Comprising 174 individually pluggable science and calibration IFUs with a near-constant data stream, MaNGA is expected to obtain ˜100 million raw-frame spectra and ˜10 million reduced galaxy spectra over the six-year lifetime of the survey. In this contribution, we describe the MaNGA Data Reduction Pipeline algorithms and centralized metadata framework that produce sky-subtracted spectrophotometrically calibrated spectra and rectified three-dimensional data cubes that combine individual dithered observations. For the 1390 galaxy data cubes released in Summer 2016 as part of SDSS-IV Data Release 13, we demonstrate that the MaNGA data have nearly Poisson-limited sky subtraction shortward of ˜8500 Å and reach a typical 10σ limiting continuum surface brightness μ = 23.5 AB arcsec-2 in a five-arcsecond-diameter aperture in the g-band. The wavelength calibration of the MaNGA data is accurate to 5 km s-1 rms, with a median spatial resolution of 2.54 arcsec FWHM (1.8 kpc at the median redshift of 0.037) and a median spectral resolution of σ = 72 km s-1.

  5. Towards a census of supercompact massive galaxies in the Kilo Degree Survey

    NASA Astrophysics Data System (ADS)

    Tortora, C.; La Barbera, F.; Napolitano, N. R.; Roy, N.; Radovich, M.; Cavuoti, S.; Brescia, M.; Longo, G.; Getman, F.; Capaccioli, M.; Grado, A.; Kuijken, K. H.; de Jong, J. T. A.; McFarland, J. P.; Puddu, E.

    2016-04-01

    The abundance of compact, massive, early-type galaxies (ETGs) provides important constraints to galaxy formation scenarios. Thanks to the area covered, depth, excellent spatial resolution and seeing, the ESO Public optical Kilo Degree Survey (KiDS), carried out with the VLT Survey Telescope, offers a unique opportunity to conduct a complete census of the most compact galaxies in the Universe. This paper presents a first census of such systems from the first 156 deg2 of KiDS. Our analysis relies on g-, r- and i-band effective radii (Re), derived by fitting galaxy images with point spread function (PSF)-convolved Sérsic models, high-quality photometric redshifts, zphot, estimated from machine learning techniques, and stellar masses, M⋆, calculated from KiDS aperture photometry. After massiveness ({M_{⋆}}≳ 8 × 10^{10} M_{⊙}) and compactness ({R_e}≲ 1.5 kpc in g, r and i bands) criteria are applied, a visual inspection of the candidates plus near-infrared photometry from VIKING-DR1 are used to refine our sample. The final catalogue, to be spectroscopically confirmed, consists of 92 systems in the redshift range z ˜ 0.2-0.7. This sample, which we expect to increase by a factor of 10 over the total survey area, represents the first attempt to select massive supercompact ETGs (MSCGs) in KiDS. We investigate the impact of redshift systematics in the selection, finding that this seems to be a major source of contamination in our sample. A preliminary analysis shows that MSCGs exhibit negative internal colour gradients, consistent with a passive evolution of these systems. We find that the number density of MSCGs is only mildly consistent with predictions from simulations at z > 0.2, while no such system is found at z < 0.2.

  6. WEAK LENSING MEASUREMENT OF GALAXY CLUSTERS IN THE CFHTLS-WIDE SURVEY

    SciTech Connect

    Shan Huanyuan; Tao Charling; Kneib, Jean-Paul; Jauzac, Mathilde; Limousin, Marceau; Fan Zuhui; Massey, Richard; Rhodes, Jason; Thanjavur, Karun; McCracken, Henry J.

    2012-03-20

    We present the first weak gravitational lensing analysis of the completed Canada-France-Hawaii Telescope Legacy Survey (CFHTLS). We study the 64 deg{sup 2} W1 field, the largest of the CFHTLS-Wide survey fields, and present the largest contiguous weak lensing convergence 'mass map' yet made. 2.66 million galaxy shapes are measured, using the Kaiser Squires and Broadhurst Method (KSB) pipeline verified against high-resolution Hubble Space Telescope imaging that covers part of the CFHTLS. Our i'-band measurements are also consistent with an analysis of independent r'-band imaging. The reconstructed lensing convergence map contains 301 peaks with signal-to-noise ratio {nu} > 3.5, consistent with predictions of a {Lambda}CDM model. Of these peaks, 126 lie within 3.'0 of a brightest central galaxy identified from multicolor optical imaging in an independent, red sequence survey. We also identify seven counterparts for massive clusters previously seen in X-ray emission within 6 deg{sup 2} XMM-LSS survey. With photometric redshift estimates for the source galaxies, we use a tomographic lensing method to fit the redshift and mass of each convergence peak. Matching these to the optical observations, we confirm 85 groups/clusters with {chi}{sup 2}{sub reduced} < 3.0, at a mean redshift (z{sub c} ) = 0.36 and velocity dispersion ({sigma}{sub c}) = 658.8 km s{sup -1}. Future surveys, such as DES, LSST, KDUST, and EUCLID, will be able to apply these techniques to map clusters in much larger volumes and thus tightly constrain cosmological models.

  7. CFHTLenS and RCSLenS: Testing Photometric Redshift Distributions Using Angular Cross-Correlations with Spectroscopic Galaxy Surveys

    NASA Astrophysics Data System (ADS)

    Choi, A.; Heymans, C.; Blake, C.; Hildebrandt, H.; Duncan, C. A. J.; Erben, T.; Nakajima, R.; Van Waerbeke, L.; Viola, M.

    2016-09-01

    We determine the accuracy of galaxy redshift distributions as estimated from photometric redshift probability distributions p(z). Our method utilises measurements of the angular cross-correlation between photometric galaxies and an overlapping sample of galaxies with spectroscopic redshifts. We describe the redshift leakage from a galaxy photometric redshift bin j into a spectroscopic redshift bin i using the sum of the p(z) for the galaxies residing in bin j. We can then predict the angular cross-correlation between photometric and spectroscopic galaxies due to intrinsic galaxy clustering when i ≠ j as a function of the measured angular cross-correlation when i = j. We also account for enhanced clustering arising from lensing magnification using a halo model. The comparison of this prediction with the measured signal provides a consistency check on the validity of using the summed p(z) to determine galaxy redshift distributions in cosmological analyses, as advocated by the Canada-France-Hawaii Telescope Lensing Survey (CFHTLenS). We present an analysis of the photometric redshifts measured by CFHTLenS, which overlaps the Baryon Oscillation Spectroscopic Survey (BOSS). We also analyse the Red-sequence Cluster Lensing Survey (RCSLenS), which overlaps both BOSS and the WiggleZ Dark Energy Survey. We find that the summed p(z) from both surveys are generally biased with respect to the true underlying distributions. If unaccounted for, this bias would lead to errors in cosmological parameter estimation from CFHTLenS by less than ˜4%. For photometric redshift bins which spatially overlap in 3-D with our spectroscopic sample, we determine redshift bias corrections which can be used in future cosmological analyses that rely on accurate galaxy redshift distributions.

  8. Unveiling the sources of disk heating in spiral galaxies with the CALIFA survey

    NASA Astrophysics Data System (ADS)

    Pinna, F.; Falcón-Barroso, J.; Martig, M.; van de Ven, G.; Lyubenova, M.; Leaman, R.

    2016-06-01

    The stellar velocity ellipsoid (SVE) quantifies the amount of velocity dispersion in the vertical, radial and azimuthal directions. Since different disk heating mechanisms (e.g. spiral arms, giant molecular clouds, mergers, etc) affect these components differently, the SVE can constrain the sources of heating in disk galaxies. At present the 3D nature of the SVE can only be directly measured in the Milky Way but, thanks to integral-field surveys like CALIFA, we are now in position to carry out the same kind of analysis in external galaxies. For this purpose, we have gathered a sample of ~30 intermediate inclined spiral galaxies along the Hubble sequence (S0 to Scd types) with high quality stellar kinematic maps. This allows us to probe the SVE for each galaxy from different line-of-sights in different regions, and thus provide strong constraints on its shape. In this presentation we relate our preliminary findings to realistic numerical simulations of disks with different formation histories (quiescent vs mergers), and to results of previous works.

  9. SELF-CALIBRATION OF GRAVITATIONAL SHEAR-GALAXY INTRINSIC ELLIPTICITY CORRELATION IN WEAK LENSING SURVEYS

    SciTech Connect

    Zhang Pengjie

    2010-09-10

    The galaxy intrinsic alignment is a severe challenge to precision cosmic shear measurement. We propose self-calibrating the induced gravitational shear-galaxy intrinsic ellipticity correlation (the GI correlation) in weak lensing surveys with photometric redshift measurements. (1) We propose a method to extract the intrinsic ellipticity-galaxy density cross-correlation (I-g) from the galaxy ellipticity-density measurement in the same redshift bin. (2) We also find a generic scaling relation to convert the extracted I-g correlation to the necessary GI correlation. We perform a concept study under simplified conditions and demonstrate its capability to significantly reduce GI contamination. We discuss the impact of various complexities on the two key ingredients of the self-calibration technique, namely the method for extracting the I-g correlation and the scaling relation between the I-g and the GI correlation. We expect that none of them will likely be able to completely invalidate the proposed self-calibration technique.

  10. The CALIFA Survey Across the Hubble Sequence: How Galaxies Grow their Bulges and Disks

    NASA Astrophysics Data System (ADS)

    Gonzáez-Delgado, R. M.; García-Benito, R.; Pérez, E.; Cid Fernandes, R.; de Amorim, A. L.; Cortijo-Ferrero, C.; Lacerda, E. A. D.; López-Fernández, R.; Vale-Asari, R. L.; Sánchez, S.; Califa Collaboration

    2016-10-01

    We characterize in detail the radial structure of the stellar population properties of 300 galaxies in the nearby universe, observed with integral field spectroscopy in the CALIFA survey. The sample covers a wide range of Hubble types, from spheroidal to spiral galaxies, ranging in stellar masses from M*˜109 to 7×1011 ⊙. We derive the stellar mass surface density (μ⋆), light-weighted and mass-weighted ages («log age»L, «log age»M), and mass-weighted metallicity («logZ⋆ »M), applying the spectral synthesis technique. We study the mean trends with galaxy stellar mass, M⋆, and morphology (E, S0, Sa, Sb, Sbc, Sc and Sd). We confirm that more massive galaxies are more compact, older, more metal rich, and less reddened by dust. Additionally, we find that these trends are preserved spatially with the radial distance to the nucleus. Deviations from these relations appear correlated with Hubble type: earlier types are more compact, older, and more metal rich for a given M⋆, which evidences that quenching is related to morphology, but not driven by mass.

  11. Carnegie-Spitzer-IMACS Survey: The Rise of Galaxy Groups Since z=1

    NASA Astrophysics Data System (ADS)

    Williams, Rik J.; Kelson, D.; Dressler, A.; McCarthy, P.; Mulchaey, J.; Oemler, A., Jr.; Shectman, S.

    2012-01-01

    We present the first measurements of the evolution of the group stellar mass function (GSMF) since z=1 from the Carnegie-Spitzer-IMACS (CSI) Survey. CSI combines robust mass selection through Spitzer 3.6-micron photometry with low-resolution spectroscopy over a 15 deg2 area, allowing the detailed study of large group (and group/field galaxy) samples over the expected epoch of group formation. From the initial 36,000 CSI galaxy redshifts over 5 deg2, we select groups using a standard friends-of-friends algorithm in angular and redshift space, constructing the GSMF in 3 redshift bins. These mass functions agree well with GSMFs from SDSS at z=0, and with X-ray-selected cluster mass functions at higher masses and redshifts. At all masses the GSMF evolves strongly from z=0.5-1, but only weak evolution is seen in low-mass (log M* ˜ 12.0) groups since z=0.5, indicating that most of these were in place at that epoch. As the majority of low-redshift galaxies reside in groups, the group environment may therefore play an important role in the decline in star formation and evolution of galaxy structures since z=1.

  12. The Arecibo Galaxy Environment Survey - VII. A dense filament with extremely long H I streams

    NASA Astrophysics Data System (ADS)

    Taylor, R.; Minchin, R. F.; Herbst, H.; Davies, J. I.; Rodriguez, R.; Vazquez, C.

    2014-09-01

    We present completed observations of the NGC 7448 galaxy group and background volume as part of the blind neutral hydrogen Arecibo Galaxy Environment Survey. Our observations cover a region spanning 5°× 4°, over a redshift range of approximately -2000 galaxy density is extremely high (15 deg-2) and many (˜24 per cent) show signs of extended H I emission, including some features as much as 800 kpc in projected length. We describe the overall characteristics of this environment: kinematics, typical galaxy colours and mass-to-light ratios, and substructure. To aid in the cataloguing of this data set, we present a new FITS viewer (FRELLED: FITS Realtime Explorer of Low Latency in Every Dimension). This incorporates interactive source cataloguing tools which increase our source extraction speed by approximately a factor of 50.

  13. The Arecibo Legacy Fast ALFA Survey: The Galaxy Population Detected by ALFALFA

    NASA Astrophysics Data System (ADS)

    Huang, Shan; Haynes, Martha P.; Giovanelli, Riccardo; Brinchmann, Jarle

    2012-09-01

    Making use of H I 21 cm line measurements from the ALFALFA survey (α.40) and photometry from the Sloan Digital Sky Survey (SDSS) and Galaxy Evolution Explorer (GALEX), we investigate the global scaling relations and fundamental planes linking stars and gas for a sample of 9417 common galaxies: the α.40-SDSS-GALEX sample. In addition to their H I properties derived from the ALFALFA data set, stellar masses (M *) and star formation rates (SFRs) are derived from fitting the UV-optical spectral energy distributions. 96% of the α.40-SDSS-GALEX galaxies belong to the blue cloud, with the average gas fraction f H I ≡ M H I /M * ~ 1.5. A transition in star formation (SF) properties is found whereby below M * ~ 109.5 M ⊙, the slope of the star-forming sequence changes, the dispersion in the specific star formation rate (SSFR) distribution increases, and the star formation efficiency (SFE) mildly increases with M *. The evolutionary track in the SSFR-M * diagram, as well as that in the color-magnitude diagram, is linked to the H I content; below this transition mass, the SF is regulated strongly by the H I. Comparison of H I and optically selected samples over the same restricted volume shows that the H I-selected population is less evolved and has overall higher SFR and SSFR at a given stellar mass, but lower SFE and extinction, suggesting either that a bottleneck exists in the H I-to-H2 conversion or that the process of SF in the very H I-dominated galaxies obeys an unusual, low-efficiency SF law. A trend is found that, for a given stellar mass, high gas fraction galaxies reside preferentially in dark matter halos with high spin parameters. Because it represents a full census of H I-bearing galaxies at z ~ 0, the scaling relations and fundamental planes derived for the ALFALFA population can be used to assess the H I detection rate by future blind H I surveys and intensity mapping experiments at higher redshift. Based on observations made with the Arecibo

  14. Properties of galaxy groups in the Sloan Digital Sky Survey - II. Active galactic nucleus feedback and star formation truncation

    NASA Astrophysics Data System (ADS)

    Weinmann, Simone M.; van den Bosch, Frank C.; Yang, Xiaohu; Mo, H. J.; Croton, Darren J.; Moore, Ben

    2006-11-01

    Successfully reproducing the galaxy luminosity function (LF) and the bimodality in the galaxy distribution requires a mechanism that can truncate star formation in massive haloes. Current models of galaxy formation consider two such truncation mechanisms: strangulation, which acts on satellite galaxies, and active galactic nucleus (AGN) feedback, which predominantly affects central galaxies. The efficiencies of these processes set the blue fraction of galaxies, fblue(L, M), as a function of galaxy luminosity, L, and halo mass, M. In this paper, we use a galaxy group catalogue extracted from the Sloan Digital Sky Survey (SDSS) to determine fblue(L, M). To demonstrate the potential power of these data as a benchmark for galaxy formation models, we compare the results to the semi-analytical model for galaxy formation of Croton et al. Although this model accurately fits the global statistics of the galaxy population, as well as the shape of the conditional LF, there are significant discrepancies when the blue fraction of galaxies as a function of mass and luminosity is compared between the observations and the model. In particular, the model predicts (i) too many faint satellites in massive haloes, (ii) a blue fraction of satellites that is much too low, and (iii) a blue fraction of centrals that is too high and with an inverted luminosity dependence. In the same order, we argue that these discrepancies owe to (i) the neglect of tidal stripping in the semi-analytical model, (ii) the oversimplified treatment of strangulation, and (iii) improper modelling of dust extinction and/or AGN feedback. The data presented here will prove useful to test and calibrate future models of galaxy formation and, in particular, to discriminate between various models for AGN feedback and other star formation truncation mechanisms.

  15. Local starburst galaxies and their descendants. Statistics from the Sloan Digital Sky Survey

    NASA Technical Reports Server (NTRS)

    Bergvall, Nils; Marquart, Thomas; Way, Michael J.; Blomqvist, Anna; Holst, Emma; Ostlin, Goran; Zackrisson, Erik

    2016-01-01

    Despite strong interest in the starburst phenomenon in extragalactic astronomy, the concept remains ill-defined. Here we use a strict definition of starburst to examine the statistical properties of starburst galaxies in the local universe. We also seek to establish links between starburst galaxies, post-starburst (hereafter postburst) galaxies, and active galaxies. Data were selected from the Sloan Digital Sky Survey DR7. We applied a novel method of treating dust attenuation and derive star formation rates, ages, and stellar masses assuming a two-component stellar population model. Dynamical masses are calculated from the width of the H-alpha line. These masses agree excellently with the photometric masses. The mass (gas+stars) range is approximately 10( exp 9) - 10(exp 11.5) solar mass. As a selection criterion for starburst galaxies, we use, the birthrate parameter, b = SFR/SFR, requiring that b is greater than 3. For postburst galaxies, we use, the equivalent width of Hdelta in absorption with the criterion EW (sub Hdelta_abs) is greater than 6 A. Results. We find that only 1% of star-forming galaxies are starburst galaxies. They contribute 3-6% to the stellar production and are therefore unimportant for the local star formation activity. The median starburst age is 70 Myr roughly independent of mass, indicating that star formation is mainly regulated by local feedback processes. The b-parameter strongly depends on burst age. Values close to b = 60 are found at ages approximately 10 Myr, while almost no starbursts are found at ages greater than 1 Gyr. The median baryonic burst mass fraction of sub-L galaxies is 5% and decreases slowly towards high masses. The median mass fraction of the recent burst in the postburst sample is 5-10%. A smaller fraction of the postburst galaxies, however, originates in non-bursting galaxies. The age-mass distribution of the postburst progenitors (with mass fractions is greater than 3%) is bimodal with a break at logM(solar mass

  16. AN ARECIBO SURVEY FOR ZEEMAN SPLITTING IN OH MEGAMASER GALAXIES

    SciTech Connect

    McBride, James; Heiles, Carl E-mail: heiles@astro.berkeley.edu

    2013-01-20

    We present the results of a comprehensive survey using the Arecibo Observatory for Zeeman splitting of OH lines in OH megamasers (OHMs). A total of 77 sources were observed with the Arecibo telescope. Of these, maser emission could not be detected for eight sources, and two sources were only ambiguously detected. Another 27 sources were detected at low signal-to-noise ratios or with interference that prevented placing any useful limits on the presence of magnetic fields. In 26 sources, it was possible to place upper limits on the magnitude of magnetic fields, typically between 10 and 30 mG. For 14 sources, the Stokes V spectra exhibit features consistent with Zeeman splitting. Eleven of these 14 are new detections, and the remaining three are re-detections of Stokes V detections in Robishaw et al. Among confident new detections, we derive magnetic fields associated with maser regions with magnitudes ranging from 6.1 to 27.6 mG. The distribution of magnetic field strengths suggests the magnetic fields in OH masing clouds in OHMs are larger than those in Galactic OH masers. The results are consistent with magnetic fields playing a dynamically important role in OH masing clouds in OHMs.

  17. Unveiling the Structure of Barred Galaxies at 3.6 μm with the Spitzer Survey of Stellar Structure in Galaxies (S4G). I. Disk Breaks

    NASA Astrophysics Data System (ADS)

    Kim, Taehyun; Gadotti, Dimitri A.; Sheth, Kartik; Athanassoula, E.; Bosma, Albert; Lee, Myung Gyoon; Madore, Barry F.; Elmegreen, Bruce; Knapen, Johan H.; Zaritsky, Dennis; Ho, Luis C.; Comerón, Sébastien; Holwerda, Benne; Hinz, Joannah L.; Muñoz-Mateos, Juan-Carlos; Cisternas, Mauricio; Erroz-Ferrer, Santiago; Buta, Ron; Laurikainen, Eija; Salo, Heikki; Laine, Jarkko; Menéndez-Delmestre, Karín; Regan, Michael W.; de Swardt, Bonita; Gil de Paz, Armando; Seibert, Mark; Mizusawa, Trisha

    2014-02-01

    We have performed two-dimensional multicomponent decomposition of 144 local barred spiral galaxies using 3.6 μm images from the Spitzer Survey of Stellar Structure in Galaxies. Our model fit includes up to four components (bulge, disk, bar, and a point source) and, most importantly, takes into account disk breaks. We find that ignoring the disk break and using a single disk scale length in the model fit for Type II (down-bending) disk galaxies can lead to differences of 40% in the disk scale length, 10% in bulge-to-total luminosity ratio (B/T), and 25% in bar-to-total luminosity ratios. We find that for galaxies with B/T >= 0.1, the break radius to bar radius, r br/R bar, varies between 1 and 3, but as a function of B/T the ratio remains roughly constant. This suggests that in bulge-dominated galaxies the disk break is likely related to the outer Lindblad resonance of the bar and thus moves outward as the bar grows. For galaxies with small bulges, B/T < 0.1, r br/R bar spans a wide range from 1 to 6. This suggests that the mechanism that produces the break in these galaxies may be different from that in galaxies with more massive bulges. Consistent with previous studies, we conclude that disk breaks in galaxies with small bulges may originate from bar resonances that may be also coupled with the spiral arms, or be related to star formation thresholds.

  18. X-ray survey of galaxy clusters in the SDSS Stripe 82 region

    NASA Astrophysics Data System (ADS)

    Durret, Florence; Takey, Ali

    2016-07-01

    We conducted a survey of galaxy clusters detected from XMM-Newton observations covering an area of 11.25 deg^2 in the Stripe 82 region of the Sloan Digital Sky Survey (SDSS). We found 94 X-ray cluster candidates from the third XMM-Newton serendipitous source catalogue (3XMM-DR5) and correlated this list with recently published X-ray and optically selected cluster catalogues to obtain optical confirmations and redshifts (between 0.05 and 1.19, with a median of 0.36) for 54 galaxy groups/clusters. Of these, 17 are newly X-ray discovered clusters and 45 systems with spectroscopic confirmations. Among the remaining candidates, 25 sources are distant cluster candidates (beyond a redshift of 0.6). We will present preliminary results on the X-ray and optical properties of these clusters: luminosities and temperatures of the X-ray gas, and optical properties of the galaxies (morphology, luminosity functions).

  19. The CfA-Rosat Survey of Distant Clusters of Galaxies

    NASA Technical Reports Server (NTRS)

    McNamara, Brian

    1998-01-01

    We (Vikhlinin, McNamara, Forman, Jones, Hornstrup, Quintana) have completed a new survey of distant clusters of galaxies, which we use to to study cluster evolution over cosmological timescales. The clusters were identified as extended X-ray sources in 650 ROSAT PSPC images of high Galactic latitude fields. Our catalog of approximately 230 extended X-ray sources covers 160 square degrees on the sky. Ours is the largest of the several ROSAT serendipitous cluster surveys in progress (e.g. SHARC, Rosati, WARPS etc.). Using V,R,I imagery obtained at several observatories, we find that greater than 90% of the X-ray sources are associated with distant clusters of galaxies. We have obtained spectroscopic redshifts for nearly 80 clusters in our catalog, and we have measured photometric redshifts for the remaining clusters. Our sample contains more than 20 clusters at z > 0.5. I will discuss the logN-logS relationship for our clusters. Because our large survey area, we are able to confirm the evolution of the most luminous distant clusters first seen in the Einstein Extended Medium Sensitivity Survey. In addition, I will discuss the relationships between optical richness, core radius, and X-ray luminosity for distant, X-ray-selected clusters.

  20. Scale-free models of galaxies. II - A complete survey of orbits

    NASA Technical Reports Server (NTRS)

    Richstone, D. O.

    1982-01-01

    A complete set of orbits starting at over 400 distinct points spread out in the phase space of an oblate scale-free potential is investigated. Each orbit is followed for a time that corresponds to a Hubble time in a realistic galaxy potential suitable for an E5 or E6 galaxy. It is noted that none of the orbits in the survey is ergodic. All of the survey orbits are regular, visiting a region at least one dimension smaller than expected from the classical integrals of motion. Thus, for all practical purposes, they have an extra nonclassical isolating integral. Approximately 95% of the survey orbits are box orbits, the rest being pipes (formerly tubes). The survey exposes an ambiguity in the original classification scheme for orbits, which, it is noted, can be resolved on the basis of the topology of an orbit's surface of section. Nevertheless, the distinction between high order very convoluted pipes and boxes is probably artificial for practical purposes.

  1. A WISE Survey of Star Formation in the Milky Way: New Insight into Galaxy Evolution

    NASA Astrophysics Data System (ADS)

    Koenig, Xavier

    We propose to measure the recent star formation rate (SFR) in the Perseus Arm of the Milky Way galaxy and its relation to the surface density of gas, whether molecular or atomic on a range of scales from star forming clusters through large star forming complexes to the full scale of the Galactic Arm. We will test the connection between the SFR-gas relationship in the Galaxy and comparable measurements made in external galaxies in order to probe its origin and better understand the role and contribution of star formation to cosmological galaxy evolution. We also propose to study star formation that has been triggered by the recent formation of massive star clusters in order to discern the mechanisms of triggering that may be operating on super bubble size scales of more than 100 parsecs. This study will allow us to understand one of the key factors that sets the efficiency with which gas becomes stars as galaxies evolve with time. In order to achieve these goals, we will carry out a census of young stellar objects in the outer Milky Way Perseus Arm, using data gathered by the WISE and 2MASS all-sky surveys, with additional use of archival data from the Spitzer Space Telescope. We will develop and refine a young star finding algorithm that uses WISE and 2MASS photometry to identify and classify young stars and filters out contaminating objects such as background galaxies. We will measure the gas content with extinction maps made with data from 2MASS. We will test the triggered star formation models by analyzing the spatial distributions of young stars in super-bubbles and massive star forming regions in the Perseus Arm. This study will produce a key, like-for-like comparison between the extragalactic star formation rate-molecular gas relation and the Galactic relation and will advance the progress in linking Galactic and extragalactic studies of star formation, studying massive star forming regions that are representative of the major mode of star formation. The

  2. VERY STRONG EMISSION-LINE GALAXIES IN THE WFC3 INFRARED SPECTROSCOPIC PARALLEL SURVEY AND IMPLICATIONS FOR HIGH-REDSHIFT GALAXIES

    SciTech Connect

    Atek, H.; Colbert, J.; Shim, H.; Siana, B.; Bridge, C.; Scarlata, C.; Malkan, M.; Ross, N. R.; McCarthy, P.; Dressler, A.; Hathi, N. P.; Teplitz, H.; Henry, A.; Martin, C.; Bunker, A. J.; Fosbury, R. A. E.

    2011-12-20

    The WFC3 Infrared Spectroscopic Parallel Survey uses the Hubble Space Telescope (HST) infrared grism capabilities to obtain slitless spectra of thousands of galaxies over a wide redshift range including the peak of star formation history of the universe. We select a population of very strong emission-line galaxies with rest-frame equivalent widths (EWs) higher than 200 A. A total of 176 objects are found over the redshift range 0.35 < z < 2.3 in the 180 arcmin{sup 2} area that we have analyzed so far. This population consists of young and low-mass starbursts with high specific star formation rates (sSFR). After spectroscopic follow-up of one of these galaxies with Keck/Low Resolution Imaging Spectrometer, we report the detection at z = 0.7 of an extremely metal-poor galaxy with 12 + log(O/H) =7.47 {+-} 0.11. After estimating the active galactic nucleus fraction in the sample, we show that the high-EW galaxies have higher sSFR than normal star-forming galaxies at any redshift. We find that the nebular emission lines can substantially affect the total broadband flux density with a median brightening of 0.3 mag, with some examples of line contamination producing brightening of up to 1 mag. We show that the presence of strong emission lines in low-z galaxies can mimic the color-selection criteria used in the z {approx} 8 dropout surveys. In order to effectively remove low-redshift interlopers, deep optical imaging is needed, at least 1 mag deeper than the bands in which the objects are detected. Without deep optical data, most of the interlopers cannot be ruled out in the wide shallow HST imaging surveys. Finally, we empirically demonstrate that strong nebular lines can lead to an overestimation of the mass and the age of galaxies derived from fitting of their spectral energy distribution (SED). Without removing emission lines, the age and the stellar mass estimates are overestimated by a factor of 2 on average and up to a factor of 10 for the high-EW galaxies

  3. The infrared luminosities of ˜332 000 SDSS galaxies predicted from artificial neural networks and the Herschel Stripe 82 survey

    NASA Astrophysics Data System (ADS)

    Ellison, Sara L.; Teimoorinia, Hossein; Rosario, David J.; Mendel, J. Trevor

    2016-01-01

    The total infrared (IR) luminosity (LIR) can be used as a robust measure of a galaxy's star formation rate (SFR), even in the presence of an active galactic nucleus (AGN), or when optical emission lines are weak. Unfortunately, existing all sky far-IR surveys, such as the Infrared Astronomical Satellite (IRAS) and AKARI, are relatively shallow and are biased towards the highest SFR galaxies and lowest redshifts. More sensitive surveys with the Herschel Space Observatory are limited to much smaller areas. In order to construct a large sample of LIR measurements for galaxies in the nearby Universe, we employ artificial neural networks (ANNs), using 1136 galaxies in the Herschel Stripe 82 sample as the training set. The networks are validated using two independent data sets (IRAS and AKARI) and demonstrated to predict the LIR with a scatter σ ˜ 0.23 dex, and with no systematic offset. Importantly, the ANN performs well for both star-forming galaxies and those with an AGN. A public catalogue is presented with our LIR predictions which can be used to determine SFRs for 331 926 galaxies in the Sloan Digital Sky Survey (SDSS), including ˜129 000 SFRs for AGN-dominated galaxies for which SDSS SFRs have large uncertainties.

  4. ALMA REDSHIFTS OF MILLIMETER-SELECTED GALAXIES FROM THE SPT SURVEY: THE REDSHIFT DISTRIBUTION OF DUSTY STAR-FORMING GALAXIES

    SciTech Connect

    Weiss, A.; De Breuck, C.; Aravena, M.; Biggs, A. D.; Marrone, D. P.; Bothwell, M.; Vieira, J. D.; Bock, J. J.; Aguirre, J. E.; Aird, K. A.; Ashby, M. L. N.; Bayliss, M.; Benson, B. A.; Bleem, L. E.; Carlstrom, J. E.; Chang, C. L.; Bethermin, M.; Brodwin, M.; Chapman, S. C.; and others

    2013-04-10

    Using the Atacama Large Millimeter/submillimeter Array, we have conducted a blind redshift survey in the 3 mm atmospheric transmission window for 26 strongly lensed dusty star-forming galaxies (DSFGs) selected with the South Pole Telescope. The sources were selected to have S{sub 1.4{sub mm}} > 20 mJy and a dust-like spectrum and, to remove low-z sources, not have bright radio (S{sub 843{sub MHz}} < 6 mJy) or far-infrared counterparts (S{sub 100{sub {mu}m}} < 1 Jy, S{sub 60{sub {mu}m}} < 200 mJy). We robustly detect 44 line features in our survey, which we identify as redshifted emission lines of {sup 12}CO, {sup 13}CO, C I, H{sub 2}O, and H{sub 2}O{sup +}. We find one or more spectral features in 23 sources yielding a {approx}90% detection rate for this survey; in 12 of these sources we detect multiple lines, while in 11 sources we detect only a single line. For the sources with only one detected line, we break the redshift degeneracy with additional spectroscopic observations if available, or infer the most likely line identification based on photometric data. This yields secure redshifts for {approx}70% of the sample. The three sources with no lines detected are tentatively placed in the redshift desert between 1.7 < z < 2.0. The resulting mean redshift of our sample is z-bar = 3.5. This finding is in contrast to the redshift distribution of radio-identified DSFGs, which have a significantly lower mean redshift of z-bar = 2.3 and for which only 10%-15% of the population is expected to be at z > 3. We discuss the effect of gravitational lensing on the redshift distribution and compare our measured redshift distribution to that of models in the literature.

  5. THE ACS NEARBY GALAXY SURVEY TREASURY. III. CEPHEIDS IN THE OUTER DISK OF M81

    SciTech Connect

    McCommas, Les P.; Williams, Benjamin F.; Dalcanton, Julianne J.; Davis, Matthew R.; Yoachim, Peter; Dolphin, Andrew E. E-mail: jd@astro.washington.edu E-mail: mrdavis@astro.washington.edu E-mail: adolphin@ratheon.com

    2009-06-15

    The ACS Nearby Galaxy Survey Treasury (ANGST) has acquired deep ACS imaging of a field in the outer disk of the large spiral galaxy M81. These data were obtained over a total of 20 Hubble Space Telescope orbits, providing a baseline long enough to reliably identify Cepheid variable stars in the field. Fundamental mode and first overtone types have been distinguished through comparative fits with corresponding Cepheid light curve templates derived from principal component analysis of confirmed Cepheids in the Large Magellanic Cloud (LMC), Small Magellanic Cloud, and Milky Way. A distance modulus of 27.78 {+-} 0.05 {sub r} {+-} 0.14 {sub s} with a corresponding distance of 3.60 {+-} 0.23 Mpc has been calculated from a sample of 11 fundamental mode and two first overtone Cepheids (assuming an LMC distance modulus of {mu}{sub LMC} = 18.41 {+-} 0.10 {sub r} {+-} 0.13 {sub s})

  6. Galaxy evolution from deep multi-wavelength infrared surveys: a prelude to Herschel

    NASA Astrophysics Data System (ADS)

    Franceschini, A.; Rodighiero, G.; Vaccari, M.; Berta, S.; Marchetti, L.; Mainetti, G.

    2010-07-01

    Context. Studies of the generation and assembly of stellar populations in galaxies largely benefit from far-IR observations, considering that the IR flux is a close prior to the rate of star formation (the bulk of which happens in dust-obscured environments). At the same time, major episodes of nuclear AGN accretion are also dust-obscured and visible in the IR. Aims: At the end of the Spitzer cryogenic mission and the onset of the Herschel era, we review our current knowledge of galaxy evolution at IR wavelengths, and model it to achieve as far as a complete view of the evolution of cosmic sources. We also develop new tools for the analysis of background fluctuations to constrain source counts in regimes of high confusion, as it happens for the Herschel sub-mm surveys. Methods: We analysed a wide variety of new data on galaxy evolution and high-redshift source populations from Spitzer cosmological surveys, and confront them with complementary data from mm ground-based observations and constraints from the far-IR diffuse radiation, as well as preliminary results from Herschel surveys. Results: These data confirm earlier indications about a very rapid increase in galaxy volume emissivity with redshift up to z ≃ 1 [ ρ(z) ∝ (1+z)4] , the fastest evolution rate observed for galaxies at any wavelengths. The observed Spitzer counts require a combination of fast evolution for the dominant population and a bumpy spectrum with substantial PAH emission at z ~ 1 to 2. Number counts at long wavelengths (70 through 1100 μm) confirm these results. All the present data require that the fast observed evolution from z = 0 to 1 flattens around redshift 1 and then keeps approximately constant up to z ≃ 2.5 at least. Our estimated redshift-dependent bolometric comoving energy density keeps lower at z ⪆ 1.5 than some previously published results based on either large extinction corrections, or large spectral extrapolations. Conclusions: The present-day IR/sub-mm data provide

  7. Weak Gravitational Lensing by Galaxy Troughs in the Dark Energy Survey

    NASA Astrophysics Data System (ADS)

    Gruen, Daniel; Dark Energy Survey Collaboration

    2016-06-01

    The Dark Energy Survey (DES) is in the process of imaging 5000 sq. deg. of the southern sky in five broad-band filters. Its primary purpose is to constrain cosmology and the physics of dark energy using weak gravitational lensing, galaxy clusters, baryonic acoustic oscillations, and supernova distance measurements.I will give an overview of weak gravitational lensing results from early DES data, with a focus on the newly developed galaxy trough statistics. Using the latter, we have made the highest signal-to-noise lensing measurements of the low density Universe to date, probing gravity and structure formation in the underdense regime. Besides these recent results, I will give an outlook on cosmological and astrophysical applications of the trough lensing signal.

  8. Redshifts for fainter galaxies in the first CfA survey slice. II

    NASA Technical Reports Server (NTRS)

    Wegner, Gary; Thorstensen, John R.; Kurtz, Michael J.; Geller, Margaret J.; Huchra, John P.

    1990-01-01

    Redshifts were measured for 96 galaxies in right ascension alpha between 8h and 17h declination delta between 30 and 31 deg, and with m(Zwicky) in the range 15.6-15.7. These correspond to 94 of the 96 entries in the Zwicky-Nilson merged catalog. The declination range delta between 29 deg and 31 deg is now complete to m(Zwicky) = 15.7. The structures in the first 6-deg-wide slice of the Center for Astrophysics redshift survey slice (delta between 26.5 and 32.5 deg are clearly defined in the 2-deg-wide slightly deeper sample; the fainter galaxies trace the structures defined by the brighter ones.

  9. Superclusters of galaxies from the 2dF redshift survey. 2. Comparison with simulations

    SciTech Connect

    Einasto, Jaan; Einasto, M.; Saar, E.; Tago, E.; Liivamagi, L.J.; Joeveer, M.J; Suhhonenko, I.; Hutsi, G.; Jaaniste, J.; Heinamaki, P.; Muller, V.; Knebe, A.; Tucker, D.; /Fermilab

    2006-04-01

    We investigate properties of superclusters of galaxies found on the basis of the 2dF Galaxy Redshift Survey, and compare them with properties of superclusters from the Millennium Simulation.We study the dependence of various characteristics of superclusters on their distance from the observer, on their total luminosity, and on their multiplicity. The multiplicity is defined by the number of Density Field (DF) clusters in superclusters. Using the multiplicity we divide superclusters into four richness classes: poor, medium, rich and extremely rich.We show that superclusters are asymmetrical and have multi-branching filamentary structure, with the degree of asymmetry and filamentarity being higher for the more luminous and richer superclusters. The comparison of real superclusters with Millennium superclusters shows that most properties of simulated superclusters agree very well with real data, the main differences being in the luminosity and multiplicity distributions.

  10. The Pan-Andromeda Archaeological Survey: Galaxy Formation In The Near-Field

    NASA Astrophysics Data System (ADS)

    McConnachie, Alan W.

    2009-01-01

    The Pan-Andromeda Archaeological Survey (PAndAS) is a Large Program on the Canada-France-Hawaii Telescope. Over the next three years, it will map the entire haloes of M31 and M33 out to projected radii of 150kpc and 50kpc respectively, over an area of more than 320 square degrees, probing a volume of more than 15 million cubic kiloparsecs around M31 and M33, reaching to surface brightness limits of order 32 mags/sq.arcsec. PAndAS will provide the deepest and most complete panorama of galaxy haloes available, and will be used to compare to and constrain cosmological models of galaxy formation over an order of magnitude in halo mass. In this talk I will review the project, discuss its main science goals, and present first results.

  11. Testing the lognormality of the galaxy and weak lensing convergence distributions from Dark Energy Survey maps

    NASA Astrophysics Data System (ADS)

    Clerkin, L.; Kirk, D.; Manera, M.; Lahav, O.; Abdalla, F.; Amara, A.; Bacon, D.; Chang, C.; Gaztañaga, E.; Hawken, A.; Jain, B.; Joachimi, B.; Vikram, V.; Abbott, T.; Allam, S.; Armstrong, R.; Benoit-Lévy, A.; Bernstein, G. M.; Bernstein, R. A.; Bertin, E.; Brooks, D.; Burke, D. L.; Rosell, A. Carnero; Carrasco Kind, M.; Crocce, M.; Cunha, C. E.; D'Andrea, C. B.; da Costa, L. N.; Desai, S.; Diehl, H. T.; Dietrich, J. P.; Eifler, T. F.; Evrard, A. E.; Flaugher, B.; Fosalba, P.; Frieman, J.; Gerdes, D. W.; Gruen, D.; Gruendl, R. A.; Gutierrez, G.; Honscheid, K.; James, D. J.; Kent, S.; Kuehn, K.; Kuropatkin, N.; Lima, M.; Melchior, P.; Miquel, R.; Nord, B.; Plazas, A. A.; Romer, A. K.; Roodman, A.; Sanchez, E.; Schubnell, M.; Sevilla-Noarbe, I.; Smith, R. C.; Soares-Santos, M.; Sobreira, F.; Suchyta, E.; Swanson, M. E. C.; Tarle, G.; Walker, A. R.

    2016-08-01

    It is well known that the probability distribution function (PDF) of galaxy density contrast is approximately lognormal; whether the PDF of mass fluctuations derived from weak lensing convergence (κWL) is lognormal is less well established. We derive PDFs of the galaxy and projected matter density distributions via the Counts in Cells (CiC) method. We use maps of galaxies and weak lensing convergence produced from the Dark Energy Survey (DES) Science Verification data over 139 deg2. We test whether the underlying density contrast is well described by a lognormal distribution for the galaxies, the convergence and their joint PDF. We confirm that the galaxy density contrast distribution is well modeled by a lognormal PDF convolved with Poisson noise at angular scales from 10'- 40'(corresponding to physical scales of 3-10 Mpc). We note that as κWL is a weighted sum of the mass fluctuations along the line of sight, its PDF is expected to be only approximately lognormal. We find that the κWL distribution is well modeled by a lognormal PDF convolved with Gaussian shape noise at scales between 10'and 20', with a best-fit χ2/DOF of 1.11 compared to 1.84 for a Gaussian model, corresponding to p-values 0.35 and 0.07 respectively, at a scale of 10'. Above 20'a simple Gaussian model is sufficient. The joint PDF is also reasonably fitted by a bivariate lognormal. As a consistency check we compare the variances derived from the lognormal modelling with those directly measured via CiC. Our methods are validated against maps from the MICE Grand Challenge N-body simulation.

  12. The Herschel Dwarf Galaxy Survey. I. Properties of the low-metallicity ISM from PACS spectroscopy

    NASA Astrophysics Data System (ADS)

    Cormier, D.; Madden, S. C.; Lebouteiller, V.; Abel, N.; Hony, S.; Galliano, F.; Rémy-Ruyer, A.; Bigiel, F.; Baes, M.; Boselli, A.; Chevance, M.; Cooray, A.; De Looze, I.; Doublier, V.; Galametz, M.; Hughes, T.; Karczewski, O. Ł.; Lee, M.-Y.; Lu, N.; Spinoglio, L.

    2015-06-01

    Context. The far-infrared (FIR) lines are important tracers of the cooling and physical conditions of the interstellar medium (ISM) and are rapidly becoming workhorse diagnostics for galaxies throughout the universe. There are clear indications of a different behavior of these lines at low metallicity that needs to be explored. Aims: Our goal is to explain the main differences and trends observed in the FIR line emission of dwarf galaxies compared to more metal-rich galaxies, and how this translates in ISM properties. Methods: We present Herschel/PACS spectroscopic observations of the [C ii] 157 μm, [O i] 63 and 145 μm, [O iii] 88 μm, [N ii] 122 and 205 μm, and [N iii] 57 μm fine-structure cooling lines in a sample of 48 low-metallicity star-forming galaxies of the guaranteed time key program Dwarf Galaxy Survey. We correlate PACS line ratios and line-to-LTIR ratios with LTIR, LTIR/LB, metallicity, and FIR color, and interpret the observed trends in terms of ISM conditions and phase filling factors with Cloudy radiative transfer models. Results: We find that the FIR lines together account for up to 3 percent of LTIR and that star-forming regions dominate the overall emission in dwarf galaxies. Compared to metal-rich galaxies, the ratios of [O iii]88/[N ii]122 and [N iii]57/[N ii]122 are high, indicative of hard radiation fields. In the photodissociation region (PDR), the [C ii]157/[O i]63 ratio is slightly higher than in metal-rich galaxies, with a small increase with metallicity, and the [O i]145/[O i]63 ratio is generally lower than 0.1, demonstrating that optical depth effects should be small on the scales probed. The [O iii]88/[O i]63 ratio can be used as an indicator of the ionized gas/PDR filling factor, and is found to be ~4 times higher in the dwarfs than in metal-rich galaxies. The high [C ii]/LTIR, [O i]/LTIR, and [O iii]/LTIR ratios, which decrease with increasing LTIR and LTIR/LB, are interpreted as a combination of moderate far-UV fields and a low

  13. The dynamics of z ~ 1 clusters of galaxies from the GCLASS survey

    NASA Astrophysics Data System (ADS)

    Biviano, A.; van der Burg, R. F. J.; Muzzin, A.; Sartoris, B.; Wilson, G.; Yee, H. K. C.

    2016-10-01

    Context. The dynamics of clusters of galaxies and its evolution provide information on their formation and growth, on the nature of dark matter and on the evolution of the baryonic components. Poor observational constraints exist so far on the dynamics of clusters at redshift z > 0.8. Aims: We aim to constrain the internal dynamics of clusters of galaxies at redshift z ~ 1, namely their mass profile M(r), velocity anisotropy profile β(r), and pseudo-phase-space density profiles Q(r) and Qr(r), obtained from the ratio between the mass density profile and the third power of the (total and, respectively, radial) velocity dispersion profiles of cluster galaxies. Methods: We used the spectroscopic and photometric data-set of 10 clusters at 0.87 < z < 1.34 from the Gemini Cluster Astrophysics Spectroscopic Survey (GCLASS). We determined the individual cluster masses from their velocity dispersions, then stack the clusters in projected phase-space. We investigated the internal dynamics of this stack cluster, using the spatial and velocity distribution of its member galaxies. We determined the stack cluster M(r) using the MAMPOSSt method, and its β(r) by direct inversion of the Jeans equation. The procedures used to determine the two aforementioned profiles also allowed us to determine Q(r) and Qr(r). Results: Several M(r) models are statistically acceptable for the stack cluster (Burkert, Einasto, Hernquist, NFW). The stack cluster total mass concentration, c ≡ r200/r-2 = 4.0-0.6+1.0, is in agreement with theoretical expectations. The total mass distribution is less concentrated than both the cluster stellar-mass and the cluster galaxies distributions. The stack cluster β(r) indicates that galaxy orbits are isotropic near the cluster center and become increasingly radially elongated with increasing cluster-centric distance. Passive and star-forming galaxies have similar β(r). The observed β(r) is similar to that of dark matter particles in simulated cosmological

  14. The history of star-forming galaxies in the Sloan Digital Sky Survey

    NASA Astrophysics Data System (ADS)

    Asari, N. V.; Cid Fernandes, R.; Stasińska, G.; Torres-Papaqui, J. P.; Mateus, A.; Sodré, L.; Schoenell, W.; Gomes, J. M.

    2007-10-01

    This paper, the sixth in the Semi-Empirical Analysis of Galaxies series, studies the evolution of 82302 star-forming (SF) galaxies from the Sloan Digital Sky Survey. Star formation histories (SFHs) are derived from detailed spectral fits obtained with our publicly available spectral synthesis code STARLIGHT. Our main goals are to explore new ways to derive SFHs from the synthesis results and apply them to investigate how SFHs vary as a function of nebular metallicity (Zneb). A number of refinements over our previous work are introduced, including (1) an improved selection criterion; (2) a careful examination of systematic residuals around Hβ (3) self-consistent determination of nebular extinctions and metallicities; (4) tests with several Zneb estimators; (5) a study of the effects of the reddening law adopted and of the relation between nebular and stellar extinctions and the interstellar component of the NaI D doublet. Our main achievements may be summarized as follows. (1) A conventional correlation analysis is performed to study how global properties relate to Zneb, leading to the confirmation of previously known relations, such as those between Zneb and galaxy luminosity, mass, dust content, mean stellar metallicity and mean stellar age. (2) A simple formalism which compresses the results of the synthesis while at the same time yielding time-dependent star formation rates (SFR) and mass assembly histories is presented. (3) A comparison of the current SFR derived from the population synthesis with that obtained from Hα shows that these independent estimators agree very well, with a scatter of a factor of 2. An important corollary of this finding is that we now have a way to estimate SFR in galaxies hosting active galactic nuclei, where the Hα method cannot be applied. (4) Fully time-dependent SFHs were derived for all galaxies, and then averaged over six Zneb bins spanning the entire SF wing in the diagram. (5) We find that SFHs vary systematically along the

  15. Eight ultra-faint galaxy candidates discovered in year two of the Dark Energy Survey

    SciTech Connect

    Drlica-Wagner, A.

    2015-11-04

    We report the discovery of eight new ultra-faint dwarf galaxy candidates in the second year of optical imaging data from the Dark Energy Survey (DES). Six of these candidates are detected at high confidence, while two lower-confidence candidates are identified in regions of non-uniform survey coverage. The new stellar systems are found by three independent automated search techniques and are identified as overdensities of stars, consistent with the isochrone and luminosity function of an old and metal-poor simple stellar population. The new systems are faint (MV > -4.7 ) and span a range of physical sizes (17 pc < r1/2 < 181pc) and heliocentric distances (25 kpc < D < 214 kpc). All of the new systems have central surface brightnesses consistent with known ultra-faint dwarf galaxies (μ 27.5 mag arcsec -2). Roughly half of the DES candidates are more distant, less luminous, and/or have lower surface brightnesses than previously known Milky Way satellite galaxies. Most of the candidates are found in the southern part of the DES footprint close to the Magellanic Clouds. We find that the DES data alone exclude (p < 10-3) a spatially isotropic distribution of Milky Way satellites and that the observed distribution can be well, though not uniquely, described by an association between several of the DES satellites and the Magellanic system. Furthermore, our model predicts that the full sky may hold ~100 ultra-faint galaxies with physical properties comparable to the DES satellites and that 20%–30% of these would be spatially associated with the Magellanic Clouds.

  16. Eight ultra-faint galaxy candidates discovered in year two of the Dark Energy Survey

    DOE PAGES

    Drlica-Wagner, A.

    2015-11-04

    We report the discovery of eight new ultra-faint dwarf galaxy candidates in the second year of optical imaging data from the Dark Energy Survey (DES). Six of these candidates are detected at high confidence, while two lower-confidence candidates are identified in regions of non-uniform survey coverage. The new stellar systems are found by three independent automated search techniques and are identified as overdensities of stars, consistent with the isochrone and luminosity function of an old and metal-poor simple stellar population. The new systems are faint (MV > -4.7 ) and span a range of physical sizes (17 pc < r1/2more » < 181pc) and heliocentric distances (25 kpc < D⊙ < 214 kpc). All of the new systems have central surface brightnesses consistent with known ultra-faint dwarf galaxies (μ 27.5 mag arcsec -2). Roughly half of the DES candidates are more distant, less luminous, and/or have lower surface brightnesses than previously known Milky Way satellite galaxies. Most of the candidates are found in the southern part of the DES footprint close to the Magellanic Clouds. We find that the DES data alone exclude (p < 10-3) a spatially isotropic distribution of Milky Way satellites and that the observed distribution can be well, though not uniquely, described by an association between several of the DES satellites and the Magellanic system. Furthermore, our model predicts that the full sky may hold ~100 ultra-faint galaxies with physical properties comparable to the DES satellites and that 20%–30% of these would be spatially associated with the Magellanic Clouds.« less

  17. The SAMI Galaxy Survey: gas streaming and dynamical M/L in rotationally supported systems

    NASA Astrophysics Data System (ADS)

    Cecil, G.; Fogarty, L. M. R.; Richards, S.; Bland-Hawthorn, J.; Lange, R.; Moffett, A.; Catinella, B.; Cortese, L.; Ho, I.-T.; Taylor, E. N.; Bryant, J. J.; Allen, J. T.; Sweet, S. M.; Croom, S. M.; Driver, S. P.; Goodwin, M.; Kelvin, L.; Green, A. W.; Konstantopoulos, I. S.; Owers, M. S.; Lawrence, J. S.; Lorente, N. P. F.

    2016-02-01

    Line-of-sight velocities of gas and stars can constrain dark matter (DM) within rotationally supported galaxies if they trace circular orbits extensively. Photometric asymmetries may signify non-circular motions, requiring spectra with dense spatial coverage. Our integral-field spectroscopy of 178 galaxies spanned the mass range of the Sydney-AAO Multi-object integral field spectrograph (SAMI) Galaxy Survey. We derived circular speed curves (CSCs) of gas and stars from non-parametric fits out to r ˜ 2re. For 12/14 with measured H I profiles, ionized gas and H I maximum velocities agreed. We fitted mass-follows-light models to 163 galaxies by approximating the radial light profile as nested, very flattened mass homeoids viewed as a Sérsic form. Fitting broad-band spectral energy distributions to Sloan Digital Sky Survey images gave median stellar mass/light 1.7 assuming a Kroupa initial mass function (IMF) versus 2.6 dynamically. Two-thirds of the dynamical mass/light measures were consistent with star+remnant IMFs. One-fifth required upscaled starlight to fit, hence comparable mass of unobserved baryons and/or DM distributed like starlight across the SAMI aperture that came to dominate motions as the starlight CSCs declined rapidly. The rest had mass distributed differently from light. Subtracting fits of Sérsic radial profiles to 13 VIKING Z-band images revealed residual weak bars. Near the bar major axis, we assessed m = 2 streaming velocities, and found deviations usually <30 km s-1 from the CSC; three showed no deviation. Thus, asymmetries rarely influenced the CSC despite colocated shock-indicating, emission-line flux ratios in more than 2/3 of our sample.

  18. The C4 clustering algorithm: Clusters of galaxies in the Sloan Digital Sky Survey

    SciTech Connect

    Miller, Christopher J.; Nichol, Robert; Reichart, Dan; Wechsler, Risa H.; Evrard, August; Annis, James; McKay, Timothy; Bahcall, Neta; Bernardi, Mariangela; Boehringer, Hans; Connolly, Andrew; Goto, Tomo; Kniazev, Alexie; Lamb, Donald; Postman, Marc; Schneider, Donald; Sheth, Ravi; Voges, Wolfgang; /Cerro-Tololo InterAmerican Obs. /Portsmouth U., ICG /North Carolina U. /Chicago U., Astron. Astrophys. Ctr. /Chicago U., EFI /Michigan U. /Fermilab /Princeton U. Observ. /Garching, Max Planck Inst., MPE /Pittsburgh U. /Tokyo U., ICRR /Baltimore, Space Telescope Sci. /Penn State U. /Chicago U. /Stavropol, Astrophys. Observ. /Heidelberg, Max Planck Inst. Astron. /INI, SAO

    2005-03-01

    We present the ''C4 Cluster Catalog'', a new sample of 748 clusters of galaxies identified in the spectroscopic sample of the Second Data Release (DR2) of the Sloan Digital Sky Survey (SDSS). The C4 cluster-finding algorithm identifies clusters as overdensities in a seven-dimensional position and color space, thus minimizing projection effects that have plagued previous optical cluster selection. The present C4 catalog covers {approx}2600 square degrees of sky and ranges in redshift from z = 0.02 to z = 0.17. The mean cluster membership is 36 galaxies (with redshifts) brighter than r = 17.7, but the catalog includes a range of systems, from groups containing 10 members to massive clusters with over 200 cluster members with redshifts. The catalog provides a large number of measured cluster properties including sky location, mean redshift, galaxy membership, summed r-band optical luminosity (L{sub r}), velocity dispersion, as well as quantitative measures of substructure and the surrounding large-scale environment. We use new, multi-color mock SDSS galaxy catalogs, empirically constructed from the {Lambda}CDM Hubble Volume (HV) Sky Survey output, to investigate the sensitivity of the C4 catalog to the various algorithm parameters (detection threshold, choice of passbands and search aperture), as well as to quantify the purity and completeness of the C4 cluster catalog. These mock catalogs indicate that the C4 catalog is {approx_equal}90% complete and 95% pure above M{sub 200} = 1 x 10{sup 14} h{sup -1}M{sub {circle_dot}} and within 0.03 {le} z {le} 0.12. Using the SDSS DR2 data, we show that the C4 algorithm finds 98% of X-ray identified clusters and 90% of Abell clusters within 0.03 {le} z {le} 0.12. Using the mock galaxy catalogs and the full HV dark matter simulations, we show that the L{sub r} of a cluster is a more robust estimator of the halo mass (M{sub 200}) than the galaxy line-of-sight velocity dispersion or the richness of the cluster. However, if we

  19. The SLUGGS survey: the mass distribution in early-type galaxies within five effective radii and beyond

    NASA Astrophysics Data System (ADS)

    Alabi, Adebusola B.; Forbes, Duncan A.; Romanowsky, Aaron J.; Brodie, Jean P.; Strader, Jay; Janz, Joachim; Pota, Vincenzo; Pastorello, Nicola; Usher, Christopher; Spitler, Lee R.; Foster, Caroline; Jennings, Zachary G.; Villaume, Alexa; Kartha, Sreeja

    2016-08-01

    We study mass distributions within and beyond 5 effective radii (Re) in 23 early-type galaxies from the SAGES Legacy Unifying Globulars and Galaxies Survey, using their globular cluster (GC) kinematic data. The data are obtained with Keck/DEep Imaging Multi-Object Spectrograph, and consist of line-of-sight velocities for ˜3500 GCs, measured with a high precision of ˜15 km s-1 per GC and extending out to ˜13 Re. We obtain the mass distribution in each galaxy using the tracer mass estimator of Watkins et al. and account for kinematic substructures, rotation of the GC systems and galaxy flattening in our mass estimates. The observed scatter between our mass estimates and results from the literature is less than 0.2 dex. The dark matter fraction within 5 Re (fDM) increases from ˜0.6 to ˜0.8 for low- and high-mass galaxies, respectively, with some intermediate-mass galaxies (M* ˜ 1011 M⊙) having low fDM ˜ 0.3, which appears at odds with predictions from simple galaxy models. We show that these results are independent of the adopted orbital anisotropy, stellar mass-to-light (M/L) ratio, and the assumed slope of the gravitational potential. However, the low fDM in the ˜1011 M⊙ galaxies agrees with the cosmological simulations of Wu et al. where the pristine dark matter distribution has been modified by baryons during the galaxy assembly process. We find hints that these M* ˜ 1011 M⊙ galaxies with low fDM have very diffuse dark matter haloes, implying that they assembled late. Beyond 5 Re, the M/L gradients are steeper in the more massive galaxies and shallower in both low and intermediate mass galaxies.

  20. THE EMISSION BY DUST AND STARS OF NEARBY GALAXIES IN THE HERSCHEL KINGFISH SURVEY

    SciTech Connect

    Skibba, Ramin A.; Engelbracht, Charles W.; Hinz, Joannah; Dale, Daniel; Zibetti, Stefano; Groves, Brent; Meidt, Sharon; Crocker, Alison; Calzetti, Daniela; Hunt, Leslie; Johnson, Benjamin D.; Galametz, Maud; Kennicutt, Robert C.; Murphy, Eric; Armus, Lee; Appleton, Philip; Bolatto, Alberto; Brandl, Bernhard; Croxall, Kevin; Gordon, Karl D.

    2011-09-01

    Using new far-infrared imaging from the Herschel Space Observatory with ancillary data from ultraviolet (UV) to submillimeter wavelengths, we estimate the total emission from dust and stars of 62 nearby galaxies in the KINGFISH survey in a way that is as empirical and model independent as possible. We collect and exploit these data in order to measure from the spectral energy distributions (SEDs) precisely how much stellar radiation is intercepted and re-radiated by dust, and how this quantity varies with galaxy properties. By including SPIRE data, we are more sensitive to emission from cold dust grains than previous analyses at shorter wavelengths, allowing for more accurate estimates of dust temperatures and masses. The dust/stellar flux ratio, which we measure by integrating the SEDs, has a range of nearly three decades (from 10{sup -2.2} to 10{sup 0.5}). The inclusion of SPIRE data shows that estimates based on data not reaching these far-IR wavelengths are biased low by 17% on average. We find that the dust/stellar flux ratio varies with morphology and total infrared (IR) luminosity, with dwarf galaxies having faint luminosities, spirals having relatively high dust/stellar ratios and IR luminosities, and some early types having low dust/stellar ratios. We also find that dust/stellar flux ratios are related to gas-phase metallicity log(f{sub dust}/f{sub *})-bar = -0.66{+-}0.08 and -0.22 {+-} 0.12 for metal-poor and intermediate-metallicity galaxies, respectively), while the dust/stellar mass ratios are less so (differing by {approx}0.2 dex); the more metal-rich galaxies span a much wider range of the flux ratios. In addition, the substantial scatter between dust/stellar flux and dust/stellar mass indicates that the former is a poor proxy of the latter. Comparing the dust/stellar flux ratios and dust temperatures, we also show that early types tend to have slightly warmer temperatures (by up to 5 K) than spiral galaxies, which may be due to more intense

  1. Size evolution of star-forming galaxies with 2 Survey

    NASA Astrophysics Data System (ADS)

    Ribeiro, B.; Le Fèvre, O.; Tasca, L. A. M.; Lemaux, B. C.; Cassata, P.; Garilli, B.; Maccagni, D.; Zamorani, G.; Zucca, E.; Amorín, R.; Bardelli, S.; Fontana, A.; Giavalisco, M.; Hathi, N. P.; Koekemoer, A.; Pforr, J.; Tresse, L.; Dunlop, J.

    2016-08-01

    Context. The size of a galaxy encapsulates the signature of the different physical processes driving its evolution. The distribution of galaxy sizes in the Universe as a function of cosmic time is therefore a key to understand galaxy evolution. Aims: We aim to measure the average sizes and size distributions of galaxies as they are assembling before the peak in the comoving star formation rate density of the Universe to better understand the evolution of galaxies across cosmic time. Methods: We used a sample of ~1200 galaxies in the COSMOS and ECDFS fields with confirmed spectroscopic redshifts 2 ≤ zspec ≤ 4.5 in the VIMOS Ultra Deep Survey (VUDS), representative of star-forming galaxies with iAB ≤ 25. We first derived galaxy sizes by applying a classical parametric profile-fitting method using GALFIT. We then measured the total pixel area covered by a galaxy above a given surface brightness threshold, which overcomes the difficulty of measuring sizes of galaxies with irregular shapes. We then compared the results obtained for the equivalent circularized radius enclosing 100% of the measured galaxy light r100T ~2.2 to those obtained with the effective radius re,circ measured with GALFIT. Results: We find that the sizes of galaxies computed with our non-parametric approach span a wide range but remain roughly constant on average with a median value r100T ~2.2 kpc for galaxies with 2 galaxies is severely underestimating their sizes. By comparing r100T with physical parameters obtained through fitting the spectral energy distribution we find that the star-forming galaxies that are the largest at any redshift are, on average, more massive and form more stars. We discover that galaxies present more concentrated light profiles with

  2. The 2dF Galaxy Redshift Survey: Wiener reconstruction of the cosmic web

    NASA Astrophysics Data System (ADS)

    Erdoǧdu, Pirin; Lahav, Ofer; Zaroubi, Saleem; Efstathiou, George; Moody, Steve; Peacock, John A.; Colless, Matthew; Baldry, Ivan K.; Baugh, Carlton M.; Bland-Hawthorn, Joss; Bridges, Terry; Cannon, Russell; Cole, Shaun; Collins, Chris; Couch, Warrick; Dalton, Gavin; De Propris, Roberto; Driver, Simon P.; Ellis, Richard S.; Frenk, Carlos S.; Glazebrook, Karl; Jackson, Carole; Lewis, Ian; Lumsden, Stuart; Maddox, Steve; Madgwick, Darren; Norberg, Peder; Peterson, Bruce A.; Sutherland, Will; Taylor, Keith

    2004-08-01

    We reconstruct the underlying density field of the Two-degree Field Galaxy Redshift Survey (2dFGRS) for the redshift range 0.035 < z < 0.200 using the Wiener filtering method. The Wiener filter suppresses shot noise and accounts for selection and incompleteness effects. The method relies on prior knowledge of the 2dF power spectrum of fluctuations and the combination of matter density and bias parameters, however the results are only slightly affected by changes to these parameters. We present maps of the density field. We use a variable smoothing technique with two different effective resolutions: 5 and 10 h-1 Mpc at the median redshift of the survey. We identify all major superclusters and voids in the survey. In particular, we find two large superclusters and two large local voids. The full set of colour maps can be viewed on the World Wide Web at http://www.ast.cam.ac.uk/~pirin.

  3. The extended ROSAT-ESO flux limited X-ray galaxy cluster survey (REFLEX II) II. Construction and properties of the survey

    NASA Astrophysics Data System (ADS)

    Böhringer, H.; Chon, G.; Collins, C. A.; Guzzo, L.; Nowak, N.; Bobrovskyi, S.

    2013-07-01

    Context. Galaxy clusters provide unique laboratories to study astrophysical processes on large scales and are important probes for cosmology. X-ray observations are currently the best means of detecting and characterizing galaxy clusters. Therefore X-ray surveys for galaxy clusters are one of the best ways to obtain a statistical census of the galaxy cluster population. Aims: In this paper we describe the construction of the REFLEX II galaxy cluster survey based on the southern part of the ROSAT All-Sky Survey. REFLEX II extends the REFLEX I survey by a factor of about two down to a flux limit of 1.8 × 10-12 erg s cm (0.1-2.4 keV). Methods: We describe the determination of the X-ray parameters, the process of X-ray source identification, and the construction of the survey selection function. Results: The REFLEX II cluster sample comprises currently 915 objects. A standard selection function is derived for a lower source count limit of 20 photons in addition to the flux limit. The median redshift of the sample is z = 0.102. Internal consistency checks and the comparison to several other galaxy cluster surveys imply that REFLEX II is better than 90% complete with a contamination less than 10%. Conclusions: With this publication we give a comprehensive statistical description of the REFLEX II survey and provide all the complementary information necessary for a proper modeling of the survey for astrophysical and cosmological applications. Based on observations at the European Southern Observatory La Silla, ChileFull Tables 2 and 3 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/555/A30

  4. Cluster Lensing Profiles Derived from a Redshift Enhancement of Magnified BOSS-survey Galaxies

    NASA Astrophysics Data System (ADS)

    Coupon, Jean; Broadhurst, Tom; Umetsu, Keiichi

    2013-07-01

    We report the first detection of a redshift-depth enhancement of background galaxies magnified by foreground clusters. Using 300,000 BOSS survey galaxies with accurate spectroscopic redshifts, we measure their mean redshift depth behind four large samples of optically selected clusters from the Sloan Digital Sky Survey (SDSS) surveys, totaling 5000-15,000 clusters. A clear trend of increasing mean redshift toward the cluster centers is found, averaged over each of the four cluster samples. In addition, we find similar but noisier behavior for an independent X-ray sample of 158 clusters lying in the foreground of the current BOSS sky area. By adopting the mass-richness relationships appropriate for each survey, we compare our results with theoretical predictions for each of the four SDSS cluster catalogs. The radial form of this redshift enhancement is well fitted by a richness-to-mass weighted composite Navarro-Frenk-White profile with an effective mass ranging between M 200 ~ 1.4-1.8 × 1014 M ⊙ for the optically detected cluster samples, and M 200 ~ 5.0 × 1014 M ⊙ for the X-ray sample. This lensing detection helps to establish the credibility of these SDSS cluster surveys, and provides a normalization for their respective mass-richness relations. In the context of the upcoming bigBOSS, Subaru Prime Focus Spectrograph, and EUCLID-NISP spectroscopic surveys, this method represents an independent means of deriving the masses of cluster samples for examining the cosmological evolution, and provides a relatively clean consistency check of weak-lensing measurements, free from the systematic limitations of shear calibration.

  5. CLUSTER LENSING PROFILES DERIVED FROM A REDSHIFT ENHANCEMENT OF MAGNIFIED BOSS-SURVEY GALAXIES

    SciTech Connect

    Coupon, Jean; Umetsu, Keiichi; Broadhurst, Tom

    2013-07-20

    We report the first detection of a redshift-depth enhancement of background galaxies magnified by foreground clusters. Using 300,000 BOSS survey galaxies with accurate spectroscopic redshifts, we measure their mean redshift depth behind four large samples of optically selected clusters from the Sloan Digital Sky Survey (SDSS) surveys, totaling 5000-15,000 clusters. A clear trend of increasing mean redshift toward the cluster centers is found, averaged over each of the four cluster samples. In addition, we find similar but noisier behavior for an independent X-ray sample of 158 clusters lying in the foreground of the current BOSS sky area. By adopting the mass-richness relationships appropriate for each survey, we compare our results with theoretical predictions for each of the four SDSS cluster catalogs. The radial form of this redshift enhancement is well fitted by a richness-to-mass weighted composite Navarro-Frenk-White profile with an effective mass ranging between M{sub 200} {approx} 1.4-1.8 Multiplication-Sign 10{sup 14} M{sub Sun} for the optically detected cluster samples, and M{sub 200} {approx} 5.0 Multiplication-Sign 10{sup 14} M{sub Sun} for the X-ray sample. This lensing detection helps to establish the credibility of these SDSS cluster surveys, and provides a normalization for their respective mass-richness relations. In the context of the upcoming bigBOSS, Subaru Prime Focus Spectrograph, and EUCLID-NISP spectroscopic surveys, this method represents an independent means of deriving the masses of cluster samples for examining the cosmological evolution, and provides a relatively clean consistency check of weak-lensing measurements, free from the systematic limitations of shear calibration.

  6. A MEASUREMENT OF THE CORRELATION OF GALAXY SURVEYS WITH CMB LENSING CONVERGENCE MAPS FROM THE SOUTH POLE TELESCOPE

    SciTech Connect

    Bleem, L. E.; Becker, M. R.; Benson, B. A.; Carlstrom, J. E.; Chang, C. L.; Crawford, T. M.; Crites, A. T.; Van Engelen, A.; Holder, G. P.; De Haan, T.; Dobbs, M. A.; Aird, K. A.; Armstrong, R.; Ashby, M. L. N.; Biesiadzinski, T.; Brodwin, M.; Busha, M. T.; Cho, H. M.; Desai, S.; Dore, O.; and others

    2012-07-01

    We compare cosmic microwave background lensing convergence maps derived from South Pole Telescope (SPT) data with galaxy survey data from the Blanco Cosmology Survey, WISE, and a new large Spitzer/IRAC field designed to overlap with the SPT survey. Using optical and infrared catalogs covering between 17 and 68 deg{sup 2} of sky, we detect a correlation between the SPT convergence maps and each of the galaxy density maps at >4{sigma}, with zero correlation robustly ruled out in all cases. The amplitude and shape of the cross-power spectra are in good agreement with theoretical expectations and the measured galaxy bias is consistent with previous work. The detections reported here utilize a small fraction of the full 2500 deg{sup 2} SPT survey data and serve as both a proof of principle of the technique and an illustration of the potential of this emerging cosmological probe.

  7. The MOSDEF Survey: Excitation Properties of z ˜ 2.3 Star-forming Galaxies

    NASA Astrophysics Data System (ADS)

    Shapley, Alice E.; Reddy, Naveen A.; Kriek, Mariska; Freeman, William R.; Sanders, Ryan L.; Siana, Brian; Coil, Alison L.; Mobasher, Bahram; Shivaei, Irene; Price, Sedona H.; de Groot, Laura

    2015-03-01

    We present results on the excitation properties of z ˜ 2.3 galaxies using early observations from the MOSFIRE Deep Evolution Field (MOSDEF) Survey. With its coverage of the full suite of strong rest-frame optical emission lines, MOSDEF provides an unprecedented view of the rest-frame optical spectra of a representative sample of distant star-forming galaxies. We investigate the locations of z ˜ 2.3 MOSDEF galaxies in multiple emission-line diagnostic diagrams. These include the [O iii]λ5007/Hβ vs. [N ii]/Hα and [O iii]λ5007/Hβ vs. [S ii]λλ6717, 6731/Hα “BPT” diagrams, as well as the O32 vs. R23 excitation diagram. We recover the well-known offset in the star-forming sequence of high-redshift galaxies in the [O iii]λ5007/Hβ vs. [N ii]/Hα BPT diagram relative to Sloan Digital Sky Survey star-forming galaxies. However, the shift for our rest-frame optically selected sample is less significant than for rest-frame-UV selected and emission-line selected galaxies at z ˜ 2. Furthermore, we find that the offset is mass-dependent, only appearing within the low-mass half of the z ˜ 2.3 MOSDEF sample, where galaxies are shifted toward higher [N ii]/Hα at fixed [O iii]/Hβ. Within the [O iii]λ5007/Hβ vs. [S ii]/Hα and O32 vs. R23 diagrams, we find that z ˜ 2.3 galaxies are distributed like local ones, and therefore attribute the shift in the [O iii]λ5007/Hβ vs. [N ii]/Hα BPT diagram to elevated N/O abundance ratios among lower-mass ({{M}*}\\lt {{10}10} {{M}⊙ }) high-redshift galaxies. The variation in N/O ratios calls into question the use at high redshift of oxygen abundance indicators based on nitrogen lines, but the apparent invariance with redshift of the excitation sequence in the O32 vs. R23 diagram paves the way for using the combination of O32 and R23 as an unbiased metallicity indicator over a wide range in redshift. This indicator will allow for an accurate characterization of the shape and normalization of the mass

  8. Kinematical evidence for secular evolution in Spitzer Survey of Stellar Structure in Galaxies (S4G) spirals

    NASA Astrophysics Data System (ADS)

    Erroz-Ferrer, Santiago; Knapen, Johan H.; Font, Joan; Beckman, John E.

    2015-03-01

    We present a study of the kinematics of a sample of isolated spiral galaxies in the Spitzer Survey of Stellar Structure in Galaxies (S4G). We use Hα Fabry-Perot data from the GHαFaS instrument at the William Herschel Telescope (WHT) in La Palma, complemented with images at 3.6 microns, in the R band and in the Hα filter. The resulting data cubes and velocity field maps allow a complete study of the kinematics of a galaxy, including in-depth investigations of the rotation curve, velocity moment maps, velocity residual maps, gradient maps and position-velocity (PV) diagrams. We find clear evidence of the secular evolution processes going on in these galaxies, such as asymmetries in the velocity field in the bar zone, and non-circular motions, probably in response to the potential of the structural components of the galaxies, or to past or present interactions.

  9. Constraining galaxy cluster temperatures and redshifts with eROSITA survey data

    NASA Astrophysics Data System (ADS)

    Borm, K.; Reiprich, T. H.; Mohammed, I.; Lovisari, L.

    2014-07-01

    Context. The nature of dark energy is imprinted in the large-scale structure of the Universe and thus in the mass and redshift distribution of galaxy clusters. The upcoming eROSITA instrument will exploit this method of probing dark energy by detecting ~100 000 clusters of galaxies in X-rays. Aims: For a precise cosmological analysis the various galaxy cluster properties need to be measured with high precision and accuracy. To predict these characteristics of eROSITA galaxy clusters and to optimise optical follow-up observations, we estimate the precision and the accuracy with which eROSITA will be able to determine galaxy cluster temperatures and redshifts from X-ray spectra. Additionally, we present the total number of clusters for which these two properties will be available from the eROSITA survey directly. Methods: We simulate the spectra of galaxy clusters for a variety of different cluster masses and redshifts while taking into account the X-ray background as well as the instrumental response. An emission model is then fit to these spectra to recover the cluster temperature and redshift. The number of clusters with precise properties is then based on the convolution of the above fit results with the galaxy cluster mass function and an assumed eROSITA selection function. Results: During its four years of all-sky surveys, eROSITA will determine cluster temperatures with relative uncertainties of ΔT/T ≲ 10% at the 68%-confidence level for clusters up to redshifts of z ~ 0.16 which corresponds to ~1670 new clusters with precise properties. Redshift information itself will become available with a precision of Δz/ (1 + z) ≲ 10% for clusters up to z ~ 0.45. Additionally, we estimate how the number of clusters with precise properties increases with a deepening of the exposure. For the above clusters, the fraction of catastrophic failures in the fit is below 20% and in most cases it is even much smaller. Furthermore, the biases in the best-fit temperatures as

  10. The SDSS-IV Extended Baryon Oscillation Spectroscopic Survey: Luminous Red Galaxy Target Selection

    NASA Astrophysics Data System (ADS)

    Prakash, Abhishek; Licquia, Timothy C.; Newman, Jeffrey A.; Ross, Ashley J.; Myers, Adam D.; Dawson, Kyle S.; Kneib, Jean-Paul; Percival, Will J.; Bautista, Julian E.; Comparat, Johan; Tinker, Jeremy L.; Schlegel, David J.; Tojeiro, Rita; Ho, Shirley; Lang, Dustin; Rao, Sandhya M.; McBride, Cameron K.; Ben Zhu, Guangtun; Brownstein, Joel R.; Bailey, Stephen; Bolton, Adam S.; Delubac, Timothée; Mariappan, Vivek; Blanton, Michael R.; Reid, Beth; Schneider, Donald P.; Seo, Hee-Jong; Carnero Rosell, Aurelio; Prada, Francisco

    2016-06-01

    We describe the algorithm used to select the luminous red galaxy (LRG) sample for the extended Baryon Oscillation Spectroscopic Survey (eBOSS) of the Sloan Digital Sky Survey IV (SDSS-IV) using photometric data from both the SDSS and the Wide-field Infrared Survey Explorer. LRG targets are required to meet a set of color selection criteria and have z-band and i-band MODEL magnitudes z < 19.95 and 19.9 < i < 21.8, respectively. Our algorithm selects roughly 50 LRG targets per square degree, the great majority of which lie in the redshift range 0.6 < z < 1.0 (median redshift 0.71). We demonstrate that our methods are highly effective at eliminating stellar contamination and lower-redshift galaxies. We perform a number of tests using spectroscopic data from SDSS-III/BOSS ancillary programs to determine the redshift reliability of our target selection and its ability to meet the science requirements of eBOSS. The SDSS spectra are of high enough signal-to-noise ratio that at least ˜89% of the target sample yields secure redshift measurements. We also present tests of the uniformity and homogeneity of the sample, demonstrating that it should be clean enough for studies of the large-scale structure of the universe at higher redshifts than SDSS-III/BOSS LRGs reached.

  11. Dust spectral energy distributions of nearby galaxies: an insight from the Herschel Reference Survey

    NASA Astrophysics Data System (ADS)

    Ciesla, L.; Boquien, M.; Boselli, A.; Buat, V.; Cortese, L.; Bendo, G. J.; Heinis, S.; Galametz, M.; Eales, S.; Smith, M. W. L.; Baes, M.; Bianchi, S.; De Looze, I.; di Serego Alighieri, S.; Galliano, F.; Hughes, T. M.; Madden, S. C.; Pierini, D.; Rémy-Ruyer, A.; Spinoglio, L.; Vaccari, M.; Viaene, S.; Vlahakis, C.

    2014-05-01

    Although it accounts only for a small fraction of the baryonic mass, dust has a profound impact on the physical processes at play in galaxies. Thus, to understand the evolution of galaxies, it is essential not only to characterize dust properties per se, but also in relation to global galaxy properties. To do so, we derive the dust properties of galaxies in a volume limited, K-band selected sample, the Herschel Reference Survey (HRS). We gather infrared photometric data from 8 μm to 500 μm from Spitzer, WISE, IRAS, and Herschel for all of the HRS galaxies. Draine & Li (2007, ApJ, 663, 866) models are fit to the data from which the stellar contribution has been carefully removed. We find that our photometric coverage is sufficient to constrain all of the parameters of the Draine & Li models and that a strong constraint on the 20-60 μm range is mandatory to estimate the relative contribution of the photo-dissociation regions to the infrared spectral energy distribution (SED). The SED models tend to systematically underestimate the observed 500 μm flux densities, especially for low-mass systems. We provide the output parameters for all of the galaxies, i.e., the minimum intensity of the interstellar radiation field, the fraction of polycyclic aromatic hydrocarbon (PAH), the relative contribution of PDR and evolved stellar population to the dust heating, the dust mass, and the infrared luminosity. For a subsample of gas-rich galaxies, we analyze the relations between these parameters and the main integrated properties of galaxies, such as stellar mass, star formation rate, infraredluminosity, metallicity, Hα and H-band surface brightness, and the far-ultraviolet attenuation. A good correlation between the fraction of PAH and the metallicity is found, implying a weakening of the PAH emission in galaxies with low metallicities and, thus, low stellar masses. The intensity of the diffuse interstellar radiation field and the H-band and Hα surface brightnesses are

  12. The VIMOS Public Extragalactic Redshift Survey (VIPERS). Environmental effects shaping the galaxy stellar mass function

    NASA Astrophysics Data System (ADS)

    Davidzon, I.; Cucciati, O.; Bolzonella, M.; De Lucia, G.; Zamorani, G.; Arnouts, S.; Moutard, T.; Ilbert, O.; Garilli, B.; Scodeggio, M.; Guzzo, L.; Abbas, U.; Adami, C.; Bel, J.; Bottini, D.; Branchini, E.; Cappi, A.; Coupon, J.; de la Torre, S.; Di Porto, C.; Fritz, A.; Franzetti, P.; Fumana, M.; Granett, B. R.; Guennou, L.; Iovino, A.; Krywult, J.; Le Brun, V.; Le Fèvre, O.; Maccagni, D.; Małek, K.; Marulli, F.; McCracken, H. J.; Mellier, Y.; Moscardini, L.; Polletta, M.; Pollo, A.; Tasca, L. A. M.; Tojeiro, R.; Vergani, D.; Zanichelli, A.

    2016-02-01

    We exploit the first public data release of VIPERS to investigate environmental effects in the evolution of galaxies between z ~ 0.5 and 0.9. The large number of spectroscopic redshifts (more than 50 000) over an area of about 10 deg2 provides a galaxy sample with high statistical power. The accurate redshift measurements (σz = 0.00047(1 + zspec)) allow us to robustly isolate galaxies living in the lowest and highest density environments (δ< 0.7 and δ> 4, respectively) as defined in terms of spatial 3D density contrast δ. We estimate the stellar mass function of galaxies residing in these two environments and constrain the high-mass end (ℳ ≳ 1011 ℳ⊙) with unprecedented precision. We find that the galaxy stellar mass function in the densest regions has a different shape than was measured at low densities, with an enhancement of massive galaxies and a hint of a flatter (less negative) slope at z< 0.8. We normalise each mass function to the comoving volume occupied by the corresponding environment and relate estimates from different redshift bins. We observe an evolution of the stellar mass function of VIPERS galaxies in high densities, while the low-density one is nearly constant. We compare these results to semi-analytical models and find consistent environmental signatures in the simulated stellar mass functions. We discuss how the halo mass function and fraction of central/satellite galaxies depend on the environments considered, making intrinsic and environmental properties of galaxies physically coupled, hence difficult to disentangle. The evolution of our low-density regions is described well by the formalism introduced by Peng et al. (2010, ApJ, 721, 193), and is consistent with the idea that galaxies become progressively passive because of internal physical processes. The same formalism could also describe the evolution of the mass function in the high density regions, but only if a significant contribution from dry mergers is considered. Based on

  13. Cool Core Bias in Sunyaev-Zel’dovich Galaxy Cluster Surveys

    SciTech Connect

    Lin, Henry W.; McDonald, Michael; Benson, Bradford; Miller, Eric

    2015-03-18

    Sunyaev-Zeldovich (SZ) surveys find massive clusters of galaxies by measuring the inverse Compton scattering of cosmic microwave background off of intra-cluster gas. The cluster selection function from such surveys is expected to be nearly independent of redshift and cluster astrophysics. In this work, we estimate the effect on the observed SZ signal of centrally-peaked gas density profiles (cool cores) and radio emission from the brightest cluster galaxy (BCG) by creating mock observations of a sample of clusters that span the observed range of classical cooling rates and radio luminosities. For each cluster, we make simulated SZ observations by the South Pole Telescope and characterize the cluster selection function, but note that our results are broadly applicable to other SZ surveys. We find that the inclusion of a cool core can cause a change in the measured SPT significance of a cluster between 0.01%–10% at z > 0.3, increasing with cuspiness of the cool core and angular size on the sky of the cluster (i.e., decreasing redshift, increasing mass). We provide quantitative estimates of the bias in the SZ signal as a function of a gas density cuspiness parameter, redshift, mass, and the 1.4 GHz radio luminosity of the central AGN. Based on this work, we estimate that, for the Phoenix cluster (one of the strongest cool cores known), the presence of a cool core is biasing the SZ significance high by ~6%. The ubiquity of radio galaxies at the centers of cool core clusters will offset the cool core bias to varying degrees

  14. Cool Core Bias in Sunyaev-Zel’dovich Galaxy Cluster Surveys

    DOE PAGES

    Lin, Henry W.; McDonald, Michael; Benson, Bradford; Miller, Eric

    2015-03-18

    Sunyaev-Zeldovich (SZ) surveys find massive clusters of galaxies by measuring the inverse Compton scattering of cosmic microwave background off of intra-cluster gas. The cluster selection function from such surveys is expected to be nearly independent of redshift and cluster astrophysics. In this work, we estimate the effect on the observed SZ signal of centrally-peaked gas density profiles (cool cores) and radio emission from the brightest cluster galaxy (BCG) by creating mock observations of a sample of clusters that span the observed range of classical cooling rates and radio luminosities. For each cluster, we make simulated SZ observations by the Southmore » Pole Telescope and characterize the cluster selection function, but note that our results are broadly applicable to other SZ surveys. We find that the inclusion of a cool core can cause a change in the measured SPT significance of a cluster between 0.01%–10% at z > 0.3, increasing with cuspiness of the cool core and angular size on the sky of the cluster (i.e., decreasing redshift, increasing mass). We provide quantitative estimates of the bias in the SZ signal as a function of a gas density cuspiness parameter, redshift, mass, and the 1.4 GHz radio luminosity of the central AGN. Based on this work, we estimate that, for the Phoenix cluster (one of the strongest cool cores known), the presence of a cool core is biasing the SZ significance high by ~6%. The ubiquity of radio galaxies at the centers of cool core clusters will offset the cool core bias to varying degrees« less

  15. BULK FLOWS FROM GALAXY LUMINOSITIES: APPLICATION TO 2MASS REDSHIFT SURVEY AND FORECAST FOR NEXT-GENERATION DATA SETS

    SciTech Connect

    Nusser, Adi; Branchini, Enzo; Davis, Marc E-mail: branchin@fis.uniroma3.it

    2011-07-10

    We present a simple method for measuring cosmological bulk flows from large redshift surveys, based on the apparent dimming or brightening of galaxies due to their peculiar motion. It is aimed at estimating bulk flows of cosmological volumes containing large numbers of galaxies. Constraints on the bulk flow are obtained by minimizing systematic variations in galaxy luminosities with respect to a reference luminosity function measured from the whole survey. This method offers two advantages over more popular bulk flow estimators: it is independent of error-prone distance indicators and of the poorly known galaxy bias. We apply the method to the Two Micron All Sky Survey redshift survey to measure the local bulk flows of spherical shells centered on the Milky Way (MW). The result is consistent with that obtained by Nusser and Davis using the SFI++ catalogue of Tully-Fisher distance indicators. We also make an assessment of the ability of the method to constrain bulk flows at larger redshifts (z = 0.1-0.5) from next-generation data sets. As a case study we consider the planned EUCLID survey. Using this method we will be able to measure a bulk motion of {approx}200 km s{sup -1} of 10{sup 6} galaxies with photometric redshifts, at the 3{sigma} level for both z {approx} 0.15 and z {approx} 0.5. Thus, the method will allow us to put strong constraints on dark energy models as well as alternative theories for structure formation.

  16. Rotation of galaxies as a signature of cosmic strings in weak lensing surveys.

    PubMed

    Thomas, Daniel B; Contaldi, Carlo R; Magueijo, João

    2009-10-30

    Vector perturbations sourced by topological defects can generate rotations in the lensing of background galaxies. This is a potential smoking gun for the existence of defects since rotation generates a curl-like component in the weak lensing signal which is not generated by standard density perturbations at linear order. This rotation signal is calculated as generated by cosmic strings. Future large scale weak lensing surveys should be able to detect this signal even for string tensions an order of magnitude lower than current constraints. PMID:19905797

  17. The Effects of Halo Assembly Bias on Self-Calibration in Galaxy Cluster Surveys

    SciTech Connect

    Wu, Hao-Yi; Rozo, Eduardo; Wechsler, Risa H.

    2008-08-07

    Self-calibration techniques for analyzing galaxy cluster counts utilize the abundance and the clustering amplitude of dark matter halos. These properties simultaneously constrain cosmological parameters and the cluster observable-mass relation. It was recently discovered that the clustering amplitude of halos depends not only on the halo mass, but also on various secondary variables, such as the halo formation time and the concentration; these dependences are collectively termed 'assembly bias'. Applying modified Fisher matrix formalism, we explore whether these secondary variables have a significant impact on the study of dark energy properties using the self-calibration technique in current (SDSS) and the near future (DES, SPT, and LSST) cluster surveys. The impact of the secondary dependence is determined by (1) the scatter in the observable-mass relation and (2) the correlation between observable and secondary variables. We find that for optical surveys, the secondary dependence does not significantly influence an SDSS-like survey; however, it may affect a DES-like survey (given the high scatter currently expected from optical clusters) and an LSST-like survey (even for low scatter values and low correlations). For an SZ survey such as SPT, the impact of secondary dependence is insignificant if the scatter is 20% or lower but can be enhanced by the potential high scatter values introduced by a highly-correlated background. Accurate modeling of the assembly bias is necessary for cluster self-calibration in the era of precision cosmology.

  18. The Photometric and Kinematic Properties of Compact Core Galaxies in the RESOLVE Survey

    NASA Astrophysics Data System (ADS)

    Snyder, Elaine M.; Bittner, Ashley; Kannappan, Sheila; Norman, Dara J.; Hood, Callie; Brown, Samantha; Dell'Antonio, Ian P.; Eckert, Kathleen D.; Ray, Christine; RESOLVE Team

    2016-01-01

    We analyze the complete set of compact core galaxies (CCGs) in the volume-limited RESOLVE survey to investigate the formation and evolution of compact galaxies across a broad statistical distribution of environments. CCGs include both compact ellipticals (cEs) and compact cores surrounded by an envelope of gas and stars, which may represent earlier or later evolutionary stages of cEs. We select CCGs to have core-only radius <800pc, an upper limit that encompasses all of the similarly compact stellar systems (ultra compact dwarfs, cEs, nucleated dwarf ellipticals) included in the Archive of Intermediate Mass Stellar Systems (AIMSS) catalog. CCGs naturally occur in a range of environments from isolated to cluster. With GALEX NUV data, we derive star formation histories and find that a significant number of CCGs have recently formed stars. We compare velocity dispersions of CCGs derived from Gemini IFU data to velocity dispersions of other RESOLVE galaxies derived from SOAR spectroscopy. We search for CCGs offset to higher or lower dispersion in the dispersion-stellar mass relation, which may indicate tidal stripping or dissipative formation, respectively. Initial results show several CCGs following the dissipative formation track. Lastly, we compare the kinematics of cEs formed via tidal stripping in numerical simulations to our observed CCG kinematics. This work has been supported by funding from NSF grants AST-0955368 and OCI-1156614 and NASA grant HST-AR-12147.01-A.

  19. Mass assembly of galaxies from the MASSIV survey and the MIRAGE simulation sample

    NASA Astrophysics Data System (ADS)

    Amram, Philippe

    2015-08-01

    The MIRAGE (Merging & isolated high-redshift AMR galaxies, Perret et al. 2014) sample has been built in order to understand the contribution of the merger processes to the mass assembly in the MASSIV (Mass Assembly Survey with SINFONI in VVDS, Contini et al. 2012) sample. It consists of a sample of idealized simulations based on the RAMSES code; the initial conditions were designed to reproduce the physical properties of the most gas-rich young galaxies. It is composed of simulations of mergers exploring the initial parameters of mass and orientation of the disks with a spatial resolution reaching 7 parsecs. We carry out a comparative study of the MASSIV kinematical data to a set of more than 4000 pseudo-observations at z=1.7 built from simulations of the MIRAGE sample to determine the ability to detect galaxy merger signatures under the observational conditions of the SINFONI instrument. The MIRAGE simulations show (i) an absence of star formation bursts in mergers of fragmented and turbulent disks, suggesting a saturation mechanism; (ii) that the gas rich clump merging mechanism is able to control the bulge mass growth, to erode the central profile of the dark matter halo and to drive massive gas outflows into the disk plane; (iii) irrespectively of the orbital configuration and of the mass ratio between the disks a new disk of gas is reconstructed quickly after the merger.

  20. Mass Assembly of galaxies from the MASSIV survey and the MIRAGE simulation sample.

    NASA Astrophysics Data System (ADS)

    Amram, Philippe

    2015-08-01

    The MIRAGE (Merging & isolated high-redshift AMR galaxies, Perret et al. 2014) sample has been built in order to understand the contribution of the merger processes to the mass assembly in the MASSIV (Mass Assembly Survey with SINFONI in VVDS, Contini et al. 2012) sample. It consists of a sample of idealized simulations based on the RAMSES code; the initial conditions were designed to reproduce the physical properties of the most gas-rich young galaxies. It is composed of simulations of mergers exploring the initial parameters of mass and orientation of the disks with a spatial resolution reaching 7 parsecs. We carry out a comparative study of the MASSIV kinematical data to a set of more than 4000 pseudo-observations at z=1.7 built from simulations of the MIRAGE sample to determine the ability to detect galaxy merger signatures under the observational conditions of the SINFONI instrument. The MIRAGE simulations show (i) an absence of star formation bursts in mergers of fragmented and turbulent disks, suggesting a saturation mechanism; (ii) that the gas rich clump merging mechanism is able to control the bulge mass growth, to erode the central profile of the dark matter halo and to drive massive gas outflows into the disk plane; (iii) irrespectively of the orbital configuration and of the mass ratio between the disks a new disk of gas is reconstructed quickly after the merger.

  1. The XMM Cluster Survey: A Massive Galaxy Cluster at z = 1.45

    SciTech Connect

    Stanford, S A; Romer, A K; Sabirli, K; Davidson, M; Hilton, M; Viana, P P; Collins, C A; Kay, S T; Liddle, A R; Mann, R G; Miller, C J; Nichol, R C; West, M J; Conselice, C J; Spinrad, H; Stern, D; Bundy, K

    2006-05-24

    We report the discovery of XMMXCS J2215.9-1738, a massive galaxy cluster at z = 1.45, which was found in the XMM Cluster Survey. The cluster candidate was initially identified as an extended X-ray source in archival XMM data. Optical spectroscopy shows that 6 galaxies within a {approx}60 arcsec diameter region lie at z = 1.45 {+-} 0.01. Model fits to the X-ray spectra of the extended emission yield kT = 7.4{sub -1.8}{sup +2.7} keV (90% confidence); if there is an undetected central X-ray point source then kT = 6.5{sub -1.8}{sup +2.6} keV. The bolometric X-ray luminosity is L{sub x} = 4.4{sub -0.6}{sup +0.8} x 10{sup 44} ergs s{sup -1} over a 2 Mpc radial region. The measured T{sub x}, which is the highest for any known cluster at z > 1, suggests that this cluster is relatively massive for such a high redshift. The redshift of XMMXCS J2215.9-1738 is the highest currently known for a spectroscopically-confirmed cluster of galaxies.

  2. THE BLACK HOLE MASS-GALAXY LUMINOSITY RELATIONSHIP FOR SLOAN DIGITAL SKY SURVEY QUASARS

    SciTech Connect

    Salviander, S.; Shields, G. A.; Bonning, E. W. E-mail: shields@astro.as.utexas.edu

    2015-02-01

    We investigate the relationship between the mass of the central supermassive black hole, M {sub BH}, and the host galaxy luminosity, L {sub gal}, in a sample of quasars from the Sloan Digital Sky Survey Data Release 7. We use composite quasar spectra binned by black hole mass and redshift to assess galaxy features that would otherwise be overwhelmed by noise in individual spectra. The black hole mass is calculated using the photoionization method, and the host galaxy luminosity is inferred from the depth of the Ca II H+K features in the composite spectra. We evaluate the evolution in the M {sub BH}-L {sub gal} relationship by examining the redshift dependence of Δ log M {sub BH}, the offset in M {sub BH} from the local M {sub BH}-L {sub gal} relationship. There is little systematic trend in Δ log M {sub BH} out to z = 0.8. Using the width of the [O III] emission line as a proxy for the stellar velocity dispersion, σ{sub *}, we find agreement of our derived host luminosities with the locally observed Faber-Jackson relation. This supports the utility of the width of the [O III] line as a proxy for σ{sub *} in statistical studies.

  3. DISTRIBUTION OF MAXIMAL LUMINOSITY OF GALAXIES IN THE SLOAN DIGITAL SKY SURVEY

    SciTech Connect

    Taghizadeh-Popp, M.; Szalay, A. S.; Ozogany, K.; Racz, Z.

    2012-11-10

    Extreme value statistics is applied to the distribution of galaxy luminosities in the Sloan Digital Sky Survey. We analyze the DR8 Main Galaxy Sample (MGS), as well as the luminous red galaxies (LRGs). Maximal luminosities are sampled from batches consisting of elongated pencil beams in the radial direction of sight. For the MGS, results suggest a small and positive tail index {xi}, effectively ruling out the possibility of having a finite maximum cutoff luminosity, and implying that the luminosity distribution function may decay as a power law at the high-luminosity end. Assuming, however, {xi} = 0, a non-parametric comparison of the maximal luminosities with the Fisher-Tippett-Gumbel distribution (limit distribution for variables distributed by the Schechter fit) indicates a good agreement provided that uncertainties arising from both the finite batch size and the batch-size distribution are accounted for. For a volume-limited sample of LRGs, results show that they can be described as being the extremes of a luminosity distribution with an exponentially decaying tail, provided that the uncertainties related to batch-size distribution are taken care of.

  4. Sample of Wolf-Rayet galaxies from the SLOAN digital sky survey

    NASA Astrophysics Data System (ADS)

    Agienko, K. B.; Guseva, N. G.; Izotov, Yu. I.

    2013-05-01

    We have analyzed the spectra of blue compact dwarf galaxies from the SLOAN Digital Sky Survey (SDSS) Data Release 7 and created a sample of 271 galaxies with Wolf-Rayet (WR) spectral features produced by high-velocity stellar winds. A blue WR feature (bump) is a blend of the N V λλ 460.5 and 462.0 nm, N III λλ 463.4 and 464.0 nm, C III λλ 465.0 nm, C IV λ 465.8 nm, and He II λ 468.6 nm emission lines. A red WR feature (bump) is the broad C IV λ 580.8 nm emission. The blue WR bump is mainly due to emissions of nitrogen WR (WN) stars, while the red bump is fully produced by emissions of carbon WR (WC) stars. All the sample spectra show the blue WR bumps, whereas the red WR bumps are only identified in 50% of sample spectra. We have derived the numbers of early-type WC stars (WCE) and late-type WN stars (WNL) in the galaxies using the luminosities of single WC and WN stars in the red and blue bumps, respectively. The number of O stars is estimated using the Hβ luminosity. The ratio of the overall number of WR stars of different types to the number of all massive stars N(WR)/N(O + WR) decreases with decreasing metallicity, corresponding to the evolution population synthesis models.

  5. HOMOGENEOUS UGRIZ PHOTOMETRY FOR ACS VIRGO CLUSTER SURVEY GALAXIES: A NON-PARAMETRIC ANALYSIS FROM SDSS IMAGING

    SciTech Connect

    Chen, Chin-Wei; Cote, Patrick; Ferrarese, Laura; West, Andrew A.; Peng, Eric W.

    2010-11-15

    We present photometric and structural parameters for 100 ACS Virgo Cluster Survey (ACSVCS) galaxies based on homogeneous, multi-wavelength (ugriz), wide-field SDSS (DR5) imaging. These early-type galaxies, which trace out the red sequence in the Virgo Cluster, span a factor of nearly {approx}10{sup 3} in g-band luminosity. We describe an automated pipeline that generates background-subtracted mosaic images, masks field sources and measures mean shapes, total magnitudes, effective radii, and effective surface brightnesses using a model-independent approach. A parametric analysis of the surface brightness profiles is also carried out to obtain Sersic-based structural parameters and mean galaxy colors. We compare the galaxy parameters to those in the literature, including those from the ACSVCS, finding good agreement in most cases, although the sizes of the brightest, and most extended, galaxies are found to be most uncertain and model dependent. Our photometry provides an external measurement of the random errors on total magnitudes from the widely used Virgo Cluster Catalog, which we estimate to be {sigma}(B{sub T}){approx} 0.13 mag for the brightest galaxies, rising to {approx} 0.3 mag for galaxies at the faint end of our sample (B{sub T} {approx} 16). The distribution of axial ratios of low-mass ('dwarf') galaxies bears a strong resemblance to the one observed for the higher-mass ('giant') galaxies. The global structural parameters for the full galaxy sample-profile shape, effective radius, and mean surface brightness-are found to vary smoothly and systematically as a function of luminosity, with unmistakable evidence for changes in structural homology along the red sequence. As noted in previous studies, the ugriz galaxy colors show a nonlinear but smooth variation over a {approx}7 mag range in absolute magnitude, with an enhanced scatter for the faintest systems that is likely the signature of their more diverse star formation histories.

  6. Galaxy pairs in the Sloan Digital Sky Survey - III. Evidence of induced star formation from optical colours

    NASA Astrophysics Data System (ADS)

    Patton, David R.; Ellison, Sara L.; Simard, Luc; McConnachie, Alan W.; Mendel, J. Trevor

    2011-03-01

    We have assembled a large, high-quality catalogue of galaxy colours from the Sloan Digital Sky Survey Data Release 7 and have identified 21 347 galaxies in pairs spanning a range of projected separations (rp < 80 h-170 kpc), relative velocities (Δv < 10 000 km s-1, which includes projected pairs that are essential for quality control) and stellar mass ratios (from 1:10 to 10:1). We find that the red fraction of galaxies in pairs is higher than that of a control sample matched in stellar mass and redshift, and demonstrate that this difference is likely due to the fact that galaxy pairs reside in higher density environments than non-paired galaxies. We detect clear signs of interaction-induced star formation within the blue galaxies in pairs, as evidenced by a higher fraction of extremely blue galaxies, along with blueward offsets between the colours of paired versus control galaxies. These signs are strongest in close pairs (rp < 30 h-170 kpc and Δv < 200 km s-1), diminish for more widely separated pairs (rp > 60 h-170 kpc and Δv < 200 km s-1) and disappear for close projected pairs (rp < 30 h-170 kpc and Δv > 3000 km s-1). These effects are also stronger in central (fibre) colours than in global colours and are found primarily in low- to medium-density environments. Conversely, no such trends are seen in red galaxies, apart from a small reddening at small separations, which may result from residual errors with photometry in crowded fields. When interpreted in conjunction with a simple model of induced starbursts, these results are consistent with a scenario in which close pericentre passages trigger induced star formation in the centres of galaxies which are sufficiently gas rich, after which time the galaxies gradually redden as they separate and their starbursts age.

  7. DOUBLE-PEAKED NARROW EMISSION-LINE GALAXIES FROM THE SLOAN DIGITAL SKY SURVEY. I. SAMPLE AND BASIC PROPERTIES

    SciTech Connect

    Ge Junqiang; Hu Chen; Wang Jianmin; Zhang Shu; Bai Jinming

    2012-08-01

    Recently, much attention has been paid to double-peaked narrow emission-line (NEL) galaxies, some of which are suggested to be related to merging galaxies. We make a systematic search to build the largest sample of these sources from Data Release 7 of the Sloan Digital Sky Survey (SDSS). With reasonable criteria for fluxes, FWHMs of the emission lines, and separations of the peaks, we select 3030 double-peaked NEL galaxies. In light of the existence of broad Balmer lines and the locations of the two components of double-peaked NELs distinguished by the Kauffmann et al. criteria in the Baldwin-Phillips-Terlevich diagram, we find that there are 81 Type I active galactic nuclei (AGNs), 837 double Type II AGNs (2-Type II), 708 galaxies with double star-forming components (2-SF), 400 with mixed star-forming and Type II AGN components (Type II + SF), and 1004 unknown-type objects. As a by-product, a sample of galaxies (12,582) with asymmetric or top-flat profiles of emission lines is established. After visually inspecting the SDSS images of the two samples, we find 54 galaxies with dual cores. The present samples can be used to study the dynamics of merging galaxies, the triggering mechanism of black hole activity, the hierarchical growth of galaxies, and the dynamics of narrow line regions driven by outflows and a rotating disk.

  8. PROPERTIES OF SATELLITE GALAXIES IN THE SDSS PHOTOMETRIC SURVEY: LUMINOSITIES, COLORS, AND PROJECTED NUMBER DENSITY PROFILES

    SciTech Connect

    Lares, M.; Lambas, D. G.; Dominguez, M. J.

    2011-07-15

    We analyze photometric data in the Sloan Digital Sky Survey Data Release 7 (SDSS-DR7) to infer statistical properties of faint satellites associated with isolated bright galaxies (M{sub r} < -20.5) in the redshift range 0.03 < z < 0.1. The mean projected radial number density profile shows an excess of companions in the photometric sample around the primaries, with approximately a power-law shape that extends up to {approx_equal} 700 kpc. Given this overdensity signal, a suitable background subtraction method is used to study the statistical properties of the population of bound satellites, down to magnitude M{sub r} = -14.5, in the projected radial distance range 100 < r{sub p} /kpc < 3(R{sub vir}). The maximum projected distance corresponds to the range 470-660 kpc for the different samples. We have also considered a color cut consistent with the observed colors of spectroscopic satellites in nearby galaxies so that distant redshifted galaxies do not dominate the statistics. We have tested the implementation of this background subtraction procedure using a mock catalog derived from the Millennium simulation semianalytic galaxy catalog based on a {Lambda} cold dark matter model. We find that the method is effective in reproducing the true projected radial satellite number density profile and luminosity distributions, providing confidence in the results derived from SDSS data. We find that the spatial extent of satellite systems is larger for bright, red primaries. Also, we find a larger spatial distribution of blue satellites. For the different samples analyzed, we derive the average number of satellites and their luminosity distributions down to M{sub r} = -14.5. The mean number of satellites depends very strongly on host luminosity. Bright primaries (M{sub r} < -21.5) host on average {approx}6 satellites with M{sub r} < -14.5. This number is reduced for primaries with lower luminosities (-21.5 < M{sub r} < -20.5) which have less than one satellite per host. We

  9. Constraining neutrinos and dark energy with galaxy clustering in the dark energy survey

    NASA Astrophysics Data System (ADS)

    Zablocki, Alan

    2016-08-01

    We determine the forecast errors on the absolute neutrino mass scale and the equation of state of dark energy by combining synthetic data from the Dark Energy Survey (DES) and the cosmic microwave background Planck surveyor. We use angular clustering of galaxies for DES in seven redshift shells up to z ˜1.7 including cross-correlations between different redshift shells. We study models with massless and massive neutrinos and three different dark energy models: Λ cold dark matter (CDM) (w =-1 ), w CDM (constant w ), and waCDM [evolving equation of state parameter w (a )=w0+wa(1 -a )]. We include the impact of uncertainties in modeling galaxy bias using a constant and a redshift-evolving bias model. For the Λ CDM model we obtain an upper limit for the sum of neutrino masses from DES +Planck of Σ mν<0.08 eV (95% C.L.) for a fiducial mass of Σ mν=0.047 eV , with a 1 σ error of 0.02 eV, assuming perfect knowledge of galaxy bias. For the w CDM model the limit is Σ mν<0.10 eV . For a w CDM model where galaxy bias evolves with redshift, the upper limit on the sum of neutrino masses increases to 0.29 eV. DES will be able to place competitive upper limits on the sum of neutrino masses of 0.1-0.3 eV and could therefore strongly constrain the inverted mass hierarchy of neutrinos. In a w CDM model the 1 σ error on constant w is Δ w =0.03 from DES galaxy clustering and Planck. Allowing Σ mν as a free parameter increases the error on w by a factor of 2, with Δ w =0.06 . In a waCDM model, in which the dark energy equation of state varies with time, the errors are Δ w0=0.2 and Δ wa=0.42 . Including neutrinos and redshift-dependent galaxy bias increases the errors to Δ w0=0.39 and Δ wa=0.99 .

  10. Properties of luminous red galaxies in the Sloan Digital Sky Survey

    NASA Astrophysics Data System (ADS)

    Barber, Tom; Meiksin, Avery; Murphy, Tara

    2007-05-01

    We perform population-synthesis modelling of a magnitude-limited sample of 4391 luminous red galaxies selected from the Sloan Digital Sky Survey Data Release 4 (SDSS DR4). We fit measured spectral indices using a large library of high-resolution spectra, covering a wide range of metallicities and assuming an exponentially decaying star formation rate punctuated by bursts, to obtain median-likelihood estimates for the light-weighted age, metallicity, stellar mass and internal extinction for the galaxies. The ages lie predominantly in the range 4-10 Gyr, peaking near 6 Gyr, with metallicities in the range -0.4 < [Z/H] < 0.4, peaking at [Z/H] ~ 0.2. Only a few per cent of the spectra are better fitted allowing for a burst in addition to continuous star formation. For these systems, typically one-quarter to one-third of the stars are formed in the burst. The total stellar masses of all the galaxies are confined to a very narrow range around ~3 × 1011Msolar, consistent with the expected homogeneity of the sample. Our results broadly agree with those of previous groups using an independent population-synthesis code. We find, however, that our choice in priors results in ages 1-2 Gyr smaller, decreasing the peak formation epoch from about z = 2.3 to 1.3 for the stars. To describe the distribution in measured mean metallicity of the galaxies, we develop a metal evolution model incorporating stochastic star formation quenching motivated by recent attempts to account for the apparent `antihierarchical' formation of elliptical galaxies. Two scenarios emerge, a closed box with an effective stellar yield of 0.26, and an accreting box with an effective stellar yield of 0.10. Both scenarios require an initial mass function weighted towards massive stars. They also require characteristic star formation quenching times of about 108 yr, the expected lifetime of luminous quasi-stellar objects. The models predict an anticorrelation between the age and mean metallicity of the galaxies

  11. MOIRCS DEEP SURVEY. IV. EVOLUTION OF GALAXY STELLAR MASS FUNCTION BACK TO z {approx} 3

    SciTech Connect

    Kajisawa, M.; Ichikawa, T.; Yamada, T.; Akiyama, M.; Tokoku, C.; Yoshikawa, T.; Tanaka, I.; Suzuki, R.; Konishi, M.; Uchimoto, Y. K.; Ouchi, M.; Iwata, I.; Hamana, T.; Onodera, M.

    2009-09-10

    We use very deep near-infrared (NIR) imaging data obtained in MOIRCS Deep Survey (MODS) to investigate the evolution of the galaxy stellar mass function back to z {approx} 3. The MODS data reach J = 24.2, H = 23.1, and K = 23.1 (5{sigma}, Vega magnitude) over 103 arcmin{sup 2} (wide) and J = 25.1, H = 23.7, and K = 24.1 over 28 arcmin{sup 2} (deep) in the GOODS-North region. The wide and very deep NIR data allow us to measure the number density of galaxies down to low stellar mass (10{sup 9}-10{sup 10} M{sub sun}) even at high redshift with high statistical accuracy. The normalization of the mass function decreases with redshift, and the integrated stellar mass density becomes {approx}8%-18% of the local value at z {approx} 2 and {approx}4%-9% at z {approx} 3, which are consistent with results of previous studies in general fields. Furthermore, we found that the low-mass slope becomes steeper with redshift from {alpha} {approx} -1.3 at z {approx} 1 to {alpha} {approx} -1.6 at z {approx} 3 and that the evolution of the number density of low-mass (10{sup 9}-10{sup 10} M{sub sun}) galaxies is weaker than that of M* ({approx}10{sup 11} M{sub sun}) galaxies. This indicates that the contribution of low-mass galaxies to the total stellar mass density has been significant at high redshift. The steepening of the low-mass slope with redshift is an opposite trend expected from the stellar mass dependence of the specific star formation rate reported in previous studies. The present result suggests that the hierarchical merging process overwhelmed the effect of the stellar mass growth by star formation and was very important for the stellar mass assembly of these galaxies at 1 {approx}< z {approx}< 3.

  12. The Arizona Radio Observatory Survey of Molecular Gas in Nearby Normal Spiral Galaxies I: The Data

    NASA Astrophysics Data System (ADS)

    Vila-Vilaro, B.; Cepa, J.; Zabludoff, A.

    2015-06-01

    Using the ARO KP 12 m telescope, we have carried out a CO(1-0) and 13CO(1-0) survey of the central regions of 113 “normal” spiral galaxies (i.e., unperturbed and with little or no nuclear activity). Our sample spans the whole range of morphological types (T = 1-7), with distances up to 75 Mpc. The detection rates for the observed objects are 99.1% for CO(1-0) and 75.2% for 13CO(1-0), respectively. For three of the targets in our sample (i.e., NGC 0891, NGC 2903, and NGC 3521), we also carry out 13CO(1-0) mapping along their major axes, which, combined with data from the literature, reveal differences in their molecular gas properties. Analysis of the beam-matched line intensity ratios of CO(1-0)/13CO(1-0) (hereafter {R}1312) indicates that for “normal” spiral galaxies the scatter in {R}1312 is of ≈x3, and has an average value (including upper limits) of 10.4 ± 0.4 (in contrast with the values of 3-5 in typical giant molecular clouds and 13 ± 6 in Starburst Galaxies). No significant correlations (at the ≥2σ level) are found between {R}1312 and the total far-infrared (FIR) luminosity, the FIR colors, and the fraction of area sampled in the disk of each galaxy. There is a tentative (1.4σ significance) correlation between {R}1312 and morphological type along the Hubble sequence. The observed scatter in {R}1312 can be explained by intrinsic variations among the CO conversion factors. The observations presented in this work, which include the most extensive 13CO(1-0) extragalactic survey published so far on “normal” spiral galaxies are ideally suited for use in recovering the “missing” flux of interferometers with elements of similar dish sizes.

  13. The BOSS Emission-line Lens Survey. III. Strong Lensing of Lyα Emitters by Individual Galaxies

    NASA Astrophysics Data System (ADS)

    Shu, Yiping; Bolton, Adam S.; Kochanek, Christopher S.; Oguri, Masamune; Pérez-Fournon, Ismael; Zheng, Zheng; Mao, Shude; Montero-Dorta, Antonio D.; Brownstein, Joel R.; Marques-Chaves, Rui; Ménard, Brice

    2016-06-01

    We introduce the Baryon Oscillation Spectroscopic Survey (BOSS) Emission-Line Lens Survey GALaxy-Lyα EmitteR sYstems (BELLS GALLERY) Survey, which is a Hubble Space Telescope program to image a sample of galaxy-scale strong gravitational lens candidate systems with high-redshift Lyα emitters (LAEs) as the background sources. The goal of the BELLS GALLERY Survey is to illuminate dark substructures in galaxy-scale halos by exploiting the small-scale clumpiness of rest-frame far-UV emission in lensed LAEs, and to thereby constrain the slope and normalization of the substructure-mass function. In this paper, we describe in detail the spectroscopic strong-lens selection technique, which is based on methods adopted in the previous Sloan Lens ACS (SLACS) Survey, BELLS, and SLACS for the Masses Survey. We present the BELLS GALLERY sample of the 21 highest-quality galaxy-LAE candidates selected from ≈ 1.4× {10}6 galaxy spectra in the BOSS of the Sloan Digital Sky Survey III. These systems consist of massive galaxies at redshifts of approximately 0.5 strongly lensing LAEs at redshifts from 2-3. The compact nature of LAEs makes them an ideal probe of dark substructures, with a substructure-mass sensitivity that is unprecedented in other optical strong-lens samples. The magnification effect from lensing will also reveal the structure of LAEs below 100 pc scales, providing a detailed look at the sites of the most concentrated unobscured star formation in the universe. The source code used for candidate selection is available for download as a part of this release.

  14. THE ACS NEARBY GALAXY SURVEY TREASURY. XI. THE REMARKABLY UNDISTURBED NGC 2403 DISK

    SciTech Connect

    Williams, Benjamin F.; Dalcanton, Julianne J.; Stilp, Adrienne; Radburn-Smith, David; Dolphin, Andrew; Skillman, Evan D. E-mail: jd@astro.washington.edu E-mail: dolphin@raytheon.com

    2013-03-10

    We present detailed analysis of color-magnitude diagrams of NGC 2403, obtained from a deep (m {approx}< 28) Hubble Space Telescope (HST) Wide Field Planetary Camera 2 observation of the outer disk of NGC 2403, supplemented by several shallow (m {approx}< 26) HST Advanced Camera for Surveys fields. We derive the spatially resolved star formation history of NGC 2403 out to 11 disk scale lengths. In the inner portions of the galaxy, we compare the recent star formation rates (SFRs) we derive from the resolved stars with those measured using GALEX FUV + Spitzer 24{mu} fluxes, finding excellent agreement between the methods. Our measurements also show that the radial gradient in recent SFR mirrors the disk exponential profile to 11 scale lengths with no break, extending to SFR densities a factor of {approx}100 lower than those that can be measured with GALEX and Spitzer ({approx}2 Multiplication-Sign 10{sup -6} M{sub Sun} yr{sup -1} kpc{sup -2}). Furthermore, we find that the cumulative stellar mass of the disk was formed at similar times at all radii. We compare these characteristics of NGC 2403 to those of its ''morphological twins'', NGC 300 and M 33, showing that the structure and age distributions of the NGC 2403 disk are more similar to those of the relatively isolated system NGC 300 than to those of the Local Group analog M 33. We also discuss the environments and HI morphologies of these three nearby galaxies, comparing them to integrated light studies of larger samples of more distant galaxy disks. Taken together, the physical properties and evolutionary history of NGC 2403 suggest that the galaxy has had no close encounters with other M 81 group members and may be falling into the group for the first time.

  15. THE SPLASH SURVEY: SPECTROSCOPY OF 15 M31 DWARF SPHEROIDAL SATELLITE GALAXIES

    SciTech Connect

    Tollerud, Erik J.; Bullock, James S.; Yniguez, Basilio; Cooper, Michael C. E-mail: bullock@uci.edu E-mail: m.cooper@uci.edu; and others

    2012-06-10

    We present a resolved star spectroscopic survey of 15 dwarf spheroidal (dSph) satellites of the Andromeda galaxy (M31). We filter foreground contamination from Milky Way (MW) stars, noting that MW substructure is evident in this contaminant sample. We also filter M31 halo field giant stars and identify the remainder as probable dSph members. We then use these members to determine the kinematical properties of the dSphs. For the first time, we confirm that And XVIII, XXI, and XXII show kinematics consistent with bound, dark-matter-dominated galaxies. From the velocity dispersions for the full sample of dSphs we determine masses, which we combine with the size and luminosity of the galaxies to produce mass-size-luminosity scaling relations. With these scalings we determine that the M31 dSphs are fully consistent with the MW dSphs, suggesting that the well-studied MW satellite population provides a fair sample for broader conclusions. We also estimate dark matter halo masses of the satellites and find that there is no sign that the luminosity of these galaxies depends on their dark halo mass, a result consistent with what is seen for MW dwarfs. Two of the M31 dSphs (And XV, XVI) have estimated maximum circular velocities smaller than 12 km s{sup -1} (to 1{sigma}), which likely places them within the lowest-mass dark matter halos known to host stars (along with Booetes I of the MW). Finally, we use the systemic velocities of the M31 satellites to estimate the mass of the M31 halo, obtaining a virial mass consistent with previous results.

  16. Hα3: an Hα imaging survey of HI selected galaxies from ALFALFA. II. Star formation properties of galaxies in the Virgo cluster and surroundings

    NASA Astrophysics Data System (ADS)

    Gavazzi, G.; Fumagalli, M.; Fossati, M.; Galardo, V.; Grossetti, F.; Boselli, A.; Giovanelli, R.; Haynes, M. P.

    2013-05-01

    Context. We present the analysis of Hα3, an Hα narrow-band imaging follow-up survey of 409 galaxies selected from the HI Arecibo Legacy Fast ALFA Survey (ALFALFA) in the Local Supercluster, including the Virgo cluster, in the region 11h < RA < 16h ; 4o < Dec < 16°; 350 < cz < 2000 km s-1. Aims: Taking advantage of Hα3, which provides the complete census of the recent massive star formation rate (SFR) in HI-rich galaxies in the local Universe and of ancillary optical data from SDSS we explore the relations between the stellar mass, the HI mass, and the current, massive SFR of nearby galaxies in the Virgo cluster. We compare these with those of isolated galaxies in the Local Supercluster, and we investigate the role of the environment in shaping the star formation properties of galaxies at the present cosmological epoch. Methods: By using the Hα hydrogen recombination line as a tracer of recent star formation, we investigated the relationships between atomic neutral gas and newly formed stars in different environments (cluster and field), for many morphological types (spirals and dwarfs), and over a wide range of stellar masses (107.5 to 1011.5 M⊙). To quantify the degree of environmental perturbation, we adopted an updated calibration of the HI deficiency parameter which we used to divide the sample into three classes: unperturbed galaxies (DefHI ≤ 0.3), perturbed galaxies (0.3 < DefHI < 0.9), and highly perturbed galaxies (DefHI ≥ 0.9). Results: Studying the mean properties of late-type galaxies in the Local Supercluster, we find that galaxies in increasing dense local galaxy conditions (or decreasing projected angular separation from M 87) show a significant decrease in the HI content and in the mean specific SFR, along with a progressive reddening of their stellar populations. The gradual quenching of the star formation occurs outside-in, consistently with the predictions of the ram pressure model. Once considered as a whole, the Virgo cluster is

  17. The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: mock galaxy catalogues for the BOSS Final Data Release

    NASA Astrophysics Data System (ADS)

    Kitaura, Francisco-Shu; Rodríguez-Torres, Sergio; Chuang, Chia-Hsun; Zhao, Cheng; Prada, Francisco; Gil-Marín, Héctor; Guo, Hong; Yepes, Gustavo; Klypin, Anatoly; Scóccola, Claudia G.; Tinker, Jeremy; McBride, Cameron; Reid, Beth; Sánchez, Ariel G.; Salazar-Albornoz, Salvador; Grieb, Jan Niklas; Vargas-Magana, Mariana; Cuesta, Antonio J.; Neyrinck, Mark; Beutler, Florian; Comparat, Johan; Percival, Will J.; Ross, Ashley

    2016-03-01

    We reproduce the galaxy clustering catalogue from the SDSS-III Baryon Oscillation Spectroscopic Survey Final Data Release (BOSS DR11&DR12) with high fidelity on all relevant scales in order to allow a robust analysis of baryon acoustic oscillations and redshift space distortions. We have generated (6000) 12 288 MultiDark PATCHY BOSS (DR11) DR12 light cones corresponding to an effective volume of ˜192 000 [h-1 Gpc]3 (the largest ever simulated volume), including cosmic evolution in the redshift range from 0.15 to 0.75. The mocks have been calibrated using a reference galaxy catalogue based on the halo abundance matching modelling of the BOSS DR11&DR12 galaxy clustering data and on the data themselves. The production follows three steps. First, we apply the PATCHY code to generate a dark matter field and an object distribution including non-linear stochastic galaxy bias. Secondly, we run the halo/stellar distribution reconstruction HADRON code to assign masses to the various objects. This step uses the mass distribution as a function of local density and non-local indicators (i.e. tidal field tensor eigenvalues and relative halo exclusion separation for massive objects) from the reference simulation applied to the corresponding patchy dark matter and galaxy distribution. Finally, we apply the SUGAR code to build the light cones. The resulting MultiDarkPATCHY mock light cones reproduce the number density, selection function, survey geometry, and in general within 1σ, for arbitrary stellar mass bins, the power spectrum up to k = 0.3 h Mpc-1, the two-point correlation functions down to a few Mpc scales, and the three-point statistics of the BOSS DR11&DR12 galaxy samples.

  18. Virtual Sky Surveys and Multi-wavelength Investigations of Galaxy Clusters

    NASA Astrophysics Data System (ADS)

    Nord, Brian D.

    2010-12-01

    The advent of large and overlapping sky surveys brings promise of a new era in the study of galaxy clusters and dark energy. Clusters have been used for decades as faithful buoys of space-time, tracing cosmic evolution through their matter content and spatial distribution. High-fidelity tracking relies on a robust connection between observable cluster signatures and the underlying dark matter content, which is otherwise invisible. Until now, clusters have been mostly viewed through independent signals in distinct wavebands. The next era of cluster cosmology may be led by multi-variate, cross-waveband detections and analyses of clusters, where different facets of clusters can be cross-correlated to develop a more complete, unified picture of cluster populations. To these ends, in this dissertation, I perform multi-variate analyses of galaxy cluster populations and develop a simulated sky survey, with which to prepare for the next generation of multi-wavelength cluster observations. First, in a new multi-variate framework, I quantify the effects of observational biases on measures of the cluster distribution function and on cosmological constraints derived from X-ray cluster populations. I also demonstrate the indispensability of the multi-variate approach in measuring the evolution of X-ray galaxy clusters; without it, we find that the combination of scatter, intrinsic correlation and irrevocable survey flux limits substantially confuses any measure of redshift evolution. Next, I construct the Millennium Gas Simulation-Virtual Sky Survey (MGSVSS), a multi-wavelength mock sky derived from an N-body gas-dynamic simulation. The MGSVSS contains both sub-mm and optical wavelength sky signals to redshift, z = 1., in a 5 x 5deg2 field of view, with O (103) halos, O (104) optically selected clusters, and O (102) clusters selected via the Sunyaev-Zel'dovich (SZ) signature. The SZ sky also includes a minimal level of sky and instrumental noise, which nearly mimics that of

  19. The DEEP3 Galaxy Redshift Survey: Keck/DEIMOS Spectroscopy in the GOODS-N Field

    NASA Astrophysics Data System (ADS)

    Cooper, Michael C.; Aird, James A.; Coil, Alison L.; Davis, Marc; Faber, S. M.; Juneau, Stéphanie; Lotz, Jennifer M.; Nandra, Kirpal; Newman, Jeffrey A.; Willmer, Christopher N. A.; Yan, Renbin

    2011-03-01

    We present the results of spectroscopic observations in the GOODS-N field completed using DEIMOS on the Keck II telescope as part of the DEEP3 Galaxy Redshift Survey. Observations of 370 unique targets down to a limiting magnitude of R AB = 24.4 yielded 156 secure redshifts. In addition to redshift information, we provide sky-subtracted one- and two-dimensional spectra of each target. Observations were conducted following the procedures of the Team Keck Redshift Survey (TKRS), thereby producing spectra that augment the TKRS sample while maintaining the uniformity of its spectral database. The data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

  20. VizieR Online Data Catalog: GEEC2 spectroscopic survey of Galaxy groups (Balogh+, 2014)

    NASA Astrophysics Data System (ADS)

    Balogh, M. L.; McGee, S. L.; Mok, A.; Wilman, D. J.; Finoguenov, A.; Bower, R. G.; Mulchaey, J. S.; Parker, L. C.; Tanaka, M.

    2015-04-01

    GEEC2 is a spectroscopic survey of galaxies in 11 groups, one of which was serendipitously discovered in the background of the target, within the COSMOS field. The spectroscopy was obtained with GMOS-South over two semesters (2010A and 2011A). The original goal of the survey was to observe ~20 groups, with 3-4 spectroscopic masks each, to allow an investigation of the intrinsic scatter within group populations. However, repeated attempts to complete the programme have been thwarted by bad weather, scheduling conflicts at Gemini, and variance in ranking from semester to semester. Following the lack of any time awarded in 2012B, attempts to extend the sample have been abandoned for the moment. Details of the target selection and spectroscopic observations have been presented in Papers I-III. (4 data files).

  1. THICK DISKS OF EDGE-ON GALAXIES SEEN THROUGH THE SPITZER SURVEY OF STELLAR STRUCTURE IN GALAXIES (S{sup 4}G): LAIR OF MISSING BARYONS?

    SciTech Connect

    Comeron, Sebastien; Elmegreen, Bruce G.; Knapen, Johan H.; Salo, Heikki; Laine, Jarkko; Laurikainen, Eija; Athanassoula, E.; Bosma, Albert; Hinz, Joannah L.; De Paz, Armando Gil; Menendez-Delmestre, KarIn; Seibert, Mark; Ho, Luis C.; Elmegreen, Debra M.; Gadotti, Dimitri A.

    2011-11-01

    Most, if not all, disk galaxies have a thin (classical) disk and a thick disk. In most models thick disks are thought to be a necessary consequence of the disk formation and/or evolution of the galaxy. We present the results of a study of the thick disk properties in a sample of carefully selected edge-on galaxies with types ranging from T = 3 to T = 8. We fitted one-dimensional luminosity profiles with physically motivated functions-the solutions of two stellar and one gaseous isothermal coupled disks in equilibrium-which are likely to yield more accurate results than other functions used in previous studies. The images used for the fits come from the Spitzer Survey of Stellar Structure in Galaxies (S{sup 4}G). We found that thick disks are on average more massive than previously reported, mostly due to the selected fitting function. Typically, the thin and thick disks have similar masses. We also found that thick disks do not flare significantly within the observed range in galactocentric radii and that the ratio of thick-to-thin disk scale heights is higher for galaxies of earlier types. Our results tend to favor an in situ origin for most of the stars in the thick disk. In addition, the thick disk may contain a significant amount of stars coming from satellites accreted after the initial buildup of the galaxy and an extra fraction of stars coming from the secular heating of the thin disk by its own overdensities. Assigning thick disk light to the thin disk component may lead to an underestimate of the overall stellar mass in galaxies because of different mass-to-light ratios in the two disk components. On the basis of our new results, we estimate that disk stellar masses are between 10% and 50% higher than previously thought and we suggest that thick disks are a reservoir of 'local missing baryons'.

  2. Quiescent Galaxies in the 3D-HST Survey: Spectroscopic Confirmation of a Large Number of Galaxies with Relatively Old Stellar Populations at Z approx. 2

    NASA Technical Reports Server (NTRS)

    Tease, Katherine Whitaker; VanDokkum, Pieter G.; Brammer, Gabriel; Momcheva, Ivelina G.; Skelton, Rosalind; Franx, Marijn; Kriek, Mariska; Labbe, Ivo; Fumagalli, Mattia; Lundgren, Britt F.; Nelson, Erica J.; Patel, Shannon G.; Rix, Hans-Walter

    2013-01-01

    Quiescent galaxies at zeta approximately 2 have been identified in large numbers based on rest-frame colors, but only a small number of these galaxies have been spectroscopically confirmed to show that their rest-frame optical spectra show either strong Balmer or metal absorption lines. Here, we median stack the rest-frame optical spectra for 171 photometrically quiescent galaxies at 1.4 less than z less than 2.2 from the 3D-HST grism survey. In addition to H(Beta) (lambda 4861 Angstroms), we unambiguously identify metal absorption lines in the stacked spectrum, including the G band (lambda 4304 Angstroms), Mg I (lambda 5175 Angstroms), and Na i (lambda 5894 Angstroms). This finding demonstrates that galaxies with relatively old stellar populations already existed when the universe was approximately 3 Gyr old, and that rest-frame color selection techniques can efficiently select them. We find an average age of 1.3(+0.1/-0.3) Gyr when fitting a simple stellar population to the entire stack. We confirm our previous result from medium-band photometry that the stellar age varies with the colors of quiescent galaxies: the reddest 80% of galaxies are dominated by metal lines and have a relatively old mean age of 1.6(+0.5/-0.4) Gyr, whereas the bluest (and brightest) galaxies have strong Balmer lines and a spectroscopic age of 0.9(+0.2/-0.1) Gyr. Although the spectrum is dominated by an evolved stellar population, we also find [O III] and Hß emission. Interestingly, this emission is more centrally concentrated than the continuum with L(sub OIII) = 1.7 +/- 0.3 × 10(exp 40 erg s-1, indicating residual central star formation or nuclear activity.

  3. Quiescent Galaxies in the 3D-HST Survey: Spectroscopic Confirmation of a Large Number of Galaxies With Relatively Old Stellar Populations at z Approx. 2

    NASA Technical Reports Server (NTRS)

    Tease, Katherine Whitaker; vanDokkum, Pieter G.; Brammer, Gabriel; Momcheva, Ivelina; Skelton, Rosalind; Franx, Marijin; Kriek, Mariska; Labbe, Ivo; Fumagalli, Mattia; Lundgren, Britt F.; Nelson, Erica J.; Patel, Shannon G.; Rix, Hans-Walter

    2013-01-01

    Quiescent galaxies at z approx. 2 have been identified in large numbers based on rest-frame colors, but only a small number of these galaxies have been spectroscopically confirmed to show that their rest-frame optical spectra show either strong Balmer or metal absorption lines. Here, we median stack the rest-frame optical spectra for 171 photometrically quiescent galaxies at 1.4 < z < 2.2 from the 3D-HST grism survey. In addition to H (4861 ),we unambiguously identify metal absorption lines in the stacked spectrum, including the G band (4304 ),Mgi (5175 ), and Na i (5894 ). This finding demonstrates that galaxies with relatively old stellar populations already existed when the universe was approx. 3 Gyr old, and that rest-frame color selection techniques can efficiently select them. We find an average age of 1.3+0.10.3 Gyr when fitting a simple stellar population to the entire stack. We confirm our previous result from medium-band photometry that the stellar age varies with the colors of quiescent galaxies: the reddest 80 of galaxies are dominated by metal lines and have a relatively old mean age of 1.6+0.50.4 Gyr, whereas the bluest (and brightest) galaxies have strong Balmer lines and a spectroscopic age of 0.9+0.20.1 Gyr. Although the spectrum is dominated by an evolved stellar population, we also find [O iii] and H emission. Interestingly, this emission is more centrally concentrated than the continuum with LOiii = 1.7+/- 0.3 x 10(exp 40) erg/s, indicating residual central star formation or nuclear activity.